Structure used in seawater, copper alloy wire or bar forming the structure, and method for manufacturing the copper alloy wire or bar

ABSTRACT

A fish cultivation net  3  has a rhombically netted form made by arranging a large number of waved wires  6  in parallel such that the adjacent wires are entwined with each other at their curved portions  6   a . The wires  6  has a composition containing 62 to 91 mass % of Cu, 0.01 to 4 mass % of Sn, and the balance being Zn. The Cu content [Cu] and the Sn content [Sn] in terms of mass % satisfy the relationship 62≦[Cu]−0.5[Sn]≦90. The copper alloy material has a phase structure including an α phase, a γ phase, and a δ phase and the total area ratio of these phases is 95 to 100%.

This is a National Phase Application in the United States ofInternational Patent Application No. PCT/JP2005/14687 filed Aug. 10,2005, which claims priority on Japan Patent Application No. 2004-233952,filed Aug. 10, 2004. The entire disclosures of the above patentapplications are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to seawater netted structures used underor in contact with seawater, such as fish cultivation nets, seawaterintakes of power generating installations or desalinating installations,and seawater strainers of marine engines, to a copper alloy wire or barused for the netted structure, and to a method for manufacturing thecopper alloy wire or bar.

BACKGROUND ART

For example, cultivation nets used for culturing fish, such as tuna,yellowtail, or globefish, are generally made of iron or artificialfiber, such as nylon, polypropylene, or polyethylene (for example,Patent Document 1).

Unfortunately, iron cultivation nets (hereinafter referred to as ironnets) and artificial fiber cultivation nets (hereinafter referred to assynthetic nets) easily trap marine organisms, such as (“acorn shells”)and other shellfishes and algae. The marine organisms clog the mesh ofthe net and thus make it difficult for seawater to pass through themesh. Consequently, oxygen and nutrients in water cannot be sufficientlysupplied to cultivation regions, and thus cultured fish becomeanorectic. Thus, the productivity and physical strength of the culturedfish are reduced. The cultivation yield is reduced as the resistance topathogenic bacteria is weakened. Also, parasites, such as gill worms andskin worms, are easily produced. The marine organisms adhering to thenet interfere with the behavior of tuna and other migratory fish rubbingagainst the net. This can adversely affect the growth of cultured fishdue to stresses and diseases. Accordingly, it is necessary to frequentlyremove trapped marine organisms from the net and parasites from thecultured fish. Such work is hard and harsh, and requires extremely highcosts.

Furthermore, the iron net is liable to be broken in a relatively shorttime by corrosion of its wires, because iron being the constituentmaterial of the net has a low corrosion resistance to seawater. Even ifonly a part of a net is broken, cultured fish can escape from thebreakage and this results in considerable losses. The iron net thereforeneeds to be replaced at regular intervals. The iron net is generallyreplaced about every two years (or about every year, in some cases). Thelifetime of the iron net is thus very short. On the other hand, thesynthetic net more easily traps marine organisms, such as shellfishesand algae, than the iron net, and it is accordingly necessary to removethe trapped marine organisms with a frequency of more than or equal tothat of the iron net. Although the synthetic net is not corroded byseawater, it inherently has a low shearing strength. Some synthetic netsmay result in a shorter lifetime than the iron net depending oncircumstances, and may need to be replaced in a shorter time. Forreplacing a net, cultured fish must be transferred. The replacement ofthe net not only requires much effort and cost, but also producesadverse effects (for example, stresses) on the cultured fish. Thesynthetic net also needs to be coated with an antifoulant on a regularbasis. The efforts and costs for this work are also high, and the costfor disposing of the waste antifoulant cannot be ignored.

Accordingly, it has been proposed that a cultivation net made of copperalloy wires (hereinafter referred to as the copper net) be used insteadof the iron net or synthetic net having the above-describeddisadvantages (for example, Patent Document 2). In use of the coppernet, Cu ions leaching from the wires prevent marine organisms, such as(“acorn shells”), from adhering to the net (this is referred to as“antifouling property”) and sterilize or disinfect the culturingseawater region. Hence, it is not necessary to remove organisms adheringto the net. Accordingly, the efforts and costs for removing organismscan be reduced while adverse effects on cultured fish are eliminated.Furthermore, the sterilization or disinfection of culturing regions canprevent diseases of cultured fish and adverse effects of parasites asmuch as possible, thus allowing the cultured fish to grow healthily at ahigh speed.

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 10-337132

Patent Document 2: Japanese Unexamined Patent Application PublicationNo. 11-140677

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

Cultivation nets are hung under the surface of the sea. If themechanical strength of the wires of a net is insufficient, the wires maybe broken due to their own weight. The cultivation net is swung by wavesand wind and rubbed by behaviors of migratory fish. Consequently, thewires are brought into strong contact (rubbed) with each other andfinally worn out. In addition, the cultivation net undergoes repeatedcollisions with waves. The impacts by the collisions erode the wires ofthe nets, thereby making the wires thin (so-called erosion-corrosionphenomenon). Furthermore, seawater corrodes metal. The wires arecorroded by contact with seawater (this is hereinafter referred to as“seawater corrosion”). At the water line, the rate of seawater corrosionis increased by an oxygen concentration cell or other electrochemicalreaction. Therefore, a cultivation net made of wires in which any one ofthe mechanical strength, the wear resistance, the erosion-corrosionresistance, and the seawater corrosion resistance is insufficient has anunsatisfactory lifetime.

Although various materials for copper nets have been proposed, knowncopper alloys do not satisfy all the requirements for the cultivationnet in terms of the mechanical strength, the wear resistance, theerosion-corrosion resistance, and the seawater corrosion resistance. Forexample, pure copper-based alloys have problems with strength, wearresistance, and erosion-corrosion resistance; Cu—Zn copper alloys haveproblems with wear resistance, erosion-corrosion resistance, andseawater corrosion resistance including dezincification corrosionresistance; Cu—Ni copper alloys have problems with wear resistance anderosion-corrosion resistance (and besides material costs). According toexperimental results obtained by the present inventors, cultivation netsmade of known copper alloys have lifetimes shorter than or equal tothose of iron nets. For example, even a net made of naval bronze (JISC4621, CDA C46400, C46500), which is a copper alloy having a superiorseawater resistance, has only substantially the same lifetime as ironnets (lifetime of at most about two years). Since the cultivation netmade of a copper alloy uses more expensive material than the iron orsynthetic net, the copper net having such a lifetime is money-losingeven though it is advantageous in antifouling and disinfection andsterilization. The copper net has not been yet put into practical usebecause of its poor total cost efficiency including lifetime, althoughit has an antifouling, a bactericidal, and a sterilizing propertysuperior in cultivation to iron nets and synthetic nets.

Accordingly, the object of the present invention is to provide a nettedstructure used in seawater, such as a fish cultivation net, which has ahighly enhanced durability including seawater resistance, with itsinherent properties maintained, and to provide a Cu—Zn—Sn copper alloymaterial in wire or bar form suitably used for the netted structure.

Means for Solving the Problems

According to a first aspect of the present invention, a Cu—Zn—Sn copperalloy material in wire or bar form is provided which forms a seawaternetted structure intended for use under or in contact with seawater,such as a fish cultivation net. The copper alloy material is selectedfrom among the following first to sixth compositions.

A first copper alloy material has a composition containing: 62 to 91mass % (preferably 63 to 82 mass %, more preferably 64 to 77 mass %) ofCu; 0.01 to 4 mass % (preferably 0.1 to 3 mass %, more preferably 0.6 to3 mass %, most preferably 0.8 to 2.5 mass %) of Sn; and the balancebeing Zn. The compositional value Y1=[Cu]−0.5[Sn] derived from the Cucontent [Cu] and Sn content [Sn] in terms of mass % is 62 to 90(preferably 62.5 to 81, more preferably 63 to 76, most preferably 64 to74). The copper apply material has a phase structure including an αphase, a γ phase, and a δ phase, and the total area ratio of the α, γ,and δ phases is 95 to 100% (preferably 98 to 100%, more preferably 99.5to 100%).

A second copper alloy material further contains at least one element X1selected from the group consisting of As, Sb, Mg, and P, in addition tothe composition of the first copper alloy material. More specifically,the second copper alloy material has a composition containing: 62 to 91mass % (preferably 63 to 82 mass %, more preferably 64 to 77 mass %) ofCu; 0.01 to 4 mass % (preferably 0.1 to 3 mass %, more preferably 0.6 to3 mass %, most preferably 0.8 to 2.5 mass %) of Sn; at least one elementX1 selected from the group consisting of 0.02 to 0.25 mass % (preferably0.03 to 0.12 mass %) of As, 0.02 to 0.25 mass % (preferably 0.03 to 0.12mass %) of Sb, 0.001 to 0.2 mass % (preferably 0.002 to 0.15 mass %,more preferably 0.005 to 0.1 mass %) of Mg, and 0.01 to 0.25 mass %(preferably 0.02 to 0.18 mass %, more preferably 0.025 to 0.15 mass %,most preferably 0.035 to 0.12 mass %) of P; and the balance being Zn.The compositional value Y2=[Cu]−0.5[Sn]-3[P]-0.5[X0] derived from the Cucontent [Cu], Sn content [Sn], P content [P], and X1 total content [X1](except P) in terms of mass % is 62 to 90 (preferably 62.5 to 81, morepreferably 63 to 76, most preferably 64 to 74). The copper alloymaterial has a phase structure including an α phase, a γ phase, and a δphase, and the total area ratio of the α, γ, and δ phases is 95 to 100%(preferably 98 to 100%, more preferably 99.5 to 100%).

A third copper alloy material further contains at least one element X2selected from the group consisting of Al, Mn, Si, and Ni, in addition tothe composition of the first copper alloy material. More specifically,the third copper alloy material has a composition containing: 62 to 91mass % (preferably 63 to 82 mass %, more preferably 64 to 77 mass %) ofCu; 0.01 to 4 mass % (preferably 0.1 to 3 mass %, more preferably 0.6 to3 mass %, most preferably 0.8 to 2.5 mass %) of Sn; at least one elementX2 selected from the group consisting of 0.02 to 1.5 mass % (preferably0.05 to 1.2 mass %, more preferably 0.1 to 1 mass %) of Al, 0.05 to 1.5mass % (preferably 0.2 to 1 mass %) of Mn, 0.02 to 1.9 mass %(preferably 0.1 to 1 mass %) of Si, and 0.005 to 0.5 mass % (preferably0.005 to 0.1 mass %) of Ni; and the balance being Zn. The compositionalvalue Y3=[Cu]−0.5[Sn]−3.5[Si]−1.8 [Al]+[Mn]+[Ni] derived from the Cucontent [Cu], Sn content [Sn], Al content [Al], Mn content [Mn], Sicontent [Si], and Ni content [Ni] in terms of mass % is 62 to 90(preferably 62.5 to 81, more preferably 63 to 76, most preferably 64 to74). The copper alloy material has a phase structure including an αphase, a γ phase, and a 6 phase, and the total area ratio of the α, γ,and δ phases is 95 to 100% (preferably 98 to 100%, more preferably 99.5to 100%).

A fourth copper alloy material further contains the elements X1 and X2in addition to the composition of the first copper alloy material. Morespecifically, the fourth copper alloy material has a compositioncontaining: 62 to 91 mass % (preferably 63 to 82 mass %, more preferably64 to 77 mass %) of Cu; 0.01 to 4 mass % (preferably 0.1 to 3 mass %,more preferably 0.6 to 3 mass %, most preferably 0.8 to 2.5 mass %) ofSn; at least one element X1 selected from the group consisting of 0.02to 0.25 mass % (preferably 0.03 to 0.12 mass %) of As, 0.02 to 0.25 mass% (preferably 0.03 to 0.12 mass %) of Sb, 0.001 to 0.2 mass %(preferably 0.002 to 0.15 mass %, more preferably 0.005 to 0.1 mass %)of Mg, and 0.01 to 0.25 mass % (preferably 0.02 to 0.18 mass %, morepreferably 0.025 to 0.15 mass %, most preferably 0.035 to 0.12 mass %)of P; at least one element X2 selected from the group consisting of 0.02to 1.5 mass % (preferably 0.05 to 1.2 mass %, more preferably 0.1 to 1mass %) of Al, 0.05 to 1.5 mass % (preferably 0.2 to 1 mass %) of Mn,0.02 to 1.9 mass % (preferably 0.1 to 1 mass %) of Si, and 0.005 to 0.5mass % (preferably 0.005 to 0.1 mass %) of Ni; and the balance being Zn.The compositional value Y4=[Cu]−0.5[Sn]−3[P]−0.5[X1]−3.5[Si]−1.8[Al]+[Mn]+[Ni] derived from the Cu content [Cu], Sn content [Sn], Pcontent [P], total X1 content [X1] (except P), Al content [Al], Mncontent [Mn], Si content [Si], and Ni content [Ni] is 62 to 90(preferably 62.5 to 81, more preferably 63 to 76, most preferably 64 to74). The copper alloy material has a phase structure including an αphase, a γ phase, and a δ phase, and the total area ratio of the α, γ,and δ phases is 95 to 100% (preferably 98 to 100%, more preferably 99.5to 100%).

Preferably, the total area ratio of the γ and δ phases in the first tofourth copper alloy materials is 0 to 10% (more preferably 0 to 5%,still more preferably 0 to 3%).

A fifth copper alloy material has a composition containing: 62 to 91mass % (preferably 63 to 82 mass %, more preferably 64 to 77 mass %) ofCu; 0.01 to 4 mass % (preferably 0.1 to 3 mass %, more preferably 0.6 to3 mass %, most preferably 0.8 to 2.5 mass %) of Sn; 0.0008 to 0.045 mass% (preferably 0.002 to 0.029 mass %, more preferably 0.004 to 0.024 mass%, most preferably 0.006 to 0.019 mass %) of Zr; 0.01 to 0.25 mass %(preferably 0.02 to 0.18 mass %, more preferably 0.025 to 0.15 mass %,most preferably 0.035 to 0.12 mass %) of P; and the balance being Zn.The compositional value Y5=[Cu]−0.5[Sn]−3[P] derived from the Cu content[Cu], Sn content [Sn], and P content [P] in terms of mass % is 62 to 90(preferably 62.5 to 81, more preferably 63 to 76, most preferably 64 to74). The copper alloy material has a phase structure including an αphase, a γ phase, and a δ phase, and the total area ratio of the α, γ,and δ phases is 95 to 100% (preferably 98 to 100%, more preferably 99.5to 100%). Also, the average grain size of the copper alloy material is0.2 mm or less (preferably 0.1 mm or less, optimally 0.06 mm or less)after melt-solidification. The average grain size aftermelt-solidification mentioned in the fifth copper alloy material and thebelow-described sixth to eighth copper alloy materials refers to theaverage of macroscopic and/or microscopic crystal grain sizes aftermelt-solidification performed by casting or welding the copper alloymaterial, without deformation processing (extrusion, rolling, etc.) orheat treatment.

A sixth copper alloy material further contains at least one element X3selected from the group consisting of As, Sb, and Mg, in addition to thecomposition of the fifth copper alloy material. More specifically, thesixth copper alloy material has a composition containing: 62 to 91 mass% (preferably 63 to 82 mass %, more preferably 64 to 77 mass %) of Cu;0.01 to 4 mass % (preferably 0.1 to 3 mass %, more preferably 0.6 to 3mass %, most preferably 0.8 to 2.5 mass %) of Sn; 0.0008 to 0.045 mass %(preferably 0.002 to 0.029 mass %, more preferably 0.004 to 0.024 mass%, most preferably 0.006 to 0.019 mass %) of Zr; 0.01 to 0.25 mass %(preferably 0.02 to 0.18 mass %, more preferably 0.025 to 0.15 mass %,most preferably 0.035 to 0.12 mass %) of P; at least one element X3selected from the group consisting of 0.02 to 0.25 mass % (preferably0.03 to 0.12 mass %) of AS, 0.02 to 0.25 mass % (preferably 0.03 to 0.12mass %) of Sb, and 0.001 to 0.2 mass % (preferably 0.002 to 0.15 mass %,more preferably 0.005 to 0.1 mass %) of Mg; and the balance being Zn.The compositional value Y6=[Cu]−0.5[Sn]−3[P]−0.5[X3] derived from the Cucontent [Cu], Sn content [Sn], P content [P], and total X3 content [X3]in terms of mass % is 62 to 90 (preferably 62.5 to 81, more preferably63 to 76, most preferably 64 to 74). The copper alloy material has aphase structure including an α phase, a γ phase, and a δ phase, and thetotal area ratio of the α, γ, and δ phases is 95 to 100% (preferably 98to 100%, more preferably 99.5 to 100%). The average grain size aftermelt-solidification is 0.2 mm or less (preferably 0.1 mm or less, mostpreferably 0.06 mm or less).

A seventh copper alloy material further contains at least one element X4selected from the group consisting of Al, Mn, Si, and Ni in addition tothe composition of the fifth copper alloy material. More specifically,the seventh copper alloy material has a composition containing: 62 to 91mass % (preferably 63 to 82 mass %, more preferably 64 to 77 mass %) ofCu; 0.01 to 4 mass % (preferably 0.1 to 3 mass %, more preferably 0.6 to3 mass %, most preferably 0.8 to 2.5 mass %) of Sn; 0.0008 to 0.045 mass% (preferably 0.002 to 0.029 mass %, more preferably 0.004 to 0.024 mass%, most preferably 0.006 to 0.019 mass %) of Zr; 0.01 to 0.25 mass %(preferably 0.02 to 0.18 mass %, more preferably 0.025 to 0.15 mass %,most preferably 0.035 to 0.12 mass %) of P; at least one element X4selected from the group consisting of 0.02 to 1.5 mass % (preferably0.05 to 1.2 mass %, more preferably 0.1 to 1 mass %) of Al, 0.05 to 1.5mass % (preferably 0.2 to 1 mass %) of Mn, 0.02 to 1.9 mass %(preferably 0.1 to 1 mass %) of Si, and 0.005 to 0.5 mass % (preferably0.005 to 0.1 mass %) of Ni; and the balance being Zn. The compositionalvalue Y7=[Cu]−0.5[Sn]−3[P]−3.5[Si]−1.8 [Al]+[Mn]+[Ni] derived from theCu content [Cu], Sn content [Sn], P content [P], Al content [Al], Mncontent [Mn], Si content [Si], and Ni content [Ni] in terms of mass % is62 to 90 (preferably 62.5 to 81, more preferably 63 to 76, mostpreferably 64 to 74). The copper alloy material has a phase structureincluding an α phase, a γ phase, and a δ phase, and the total area ratioof the α, γ, and δ phases is 95 to 100% (preferably 98 to 100%, morepreferably 99.5 to 100%). Also, the average grain size aftermelt-solidification is 0.2 mm or less (preferably 0.1 mm or less, mostpreferably 0.06 mm or less).

A eighth copper alloy material further contains the elements X3 and X4in addition to the composition of the fifth copper alloy material. Morespecifically, the eighth copper alloy material has a compositioncontaining: 62 to 91 mass % (preferably 63 to 82 mass %, more preferably64 to 77 mass %) of Cu; 0.01 to 4 mass % (preferably 0.1 to 3 mass %,more preferably 0.6 to 3 mass %, most preferably 0.8 to 2.5 mass %) ofSn; 0.0008 to 0.045 mass % (preferably 0.002 to 0.029 mass %, morepreferably 0.004 to 0.024 mass %, most preferably 0.006 to 0.019 mass %)of Zr; 0.01 to 0.25 mass % (preferably 0.02 to 0.18 mass %, morepreferably 0.025 to 0.15 mass %, optimally 0.035 to 0.12 mass %) of P;at least one element X3 selected from the group consisting of 0.02 to0.25 mass % (preferably 0.03 to 0.12 mass %) of As, 0.02 to 0.25 mass %(preferably 0.03 to 0.12 mass %) of Sb, 0.001 to 0.2 mass % (preferably0.002 to 0.15 mass %, and more preferably 0.005 to 0.1 mass %) of Mg; atleast one element X4 selected from the group consisting of 0.02 to 1.5mass % (preferably 0.05 to 1.2 mass %, more preferably 0.1 to 1 mass %)of Al, 0.05 to 1.5 mass % (preferably 0.2 to 1 mass %) of Mn, 0.02 to1.9 mass % (preferably 0.1 to 1 mass %) of Si, and 0.005 to 0.5 mass %(preferably 0.005 to 0.1 mass %) of Ni; and the balance being Zn. Thecompositional value Y8=[Cu]−0.5[Sn]−3[P]−0.5[X3]−3.5[Si]−1.8[Al]+[Mn]+[Ni] derived from the Cu content [Cu], Sn content [Sn], Pcontent [P], total X3 content [X3], Al content [Al], Mn content [Mn], Sicontent [Si], and Ni content [Ni] in terms of mass % is 62 to 90(preferably 62.5 to 81, more preferably 63 to 76, most preferably 64 to74). The copper alloy material has a phase structure including an αphase, a γ phase, and a δ phase, and the total area ratio of the α, γ,and δ phases is 95 to 100% (preferably 98 to 100%, more preferably 99.5to 100%). Also, the average grain size after melt-solidification is 0.2mm or less (preferably 0.1 mm or less, most preferably 0.06 mm or less).

Each of the fifth to eighth copper alloy materials is prepared by addingZr and P, which are grain-refining elements, to each composition of thefirst to fourth copper alloy materials. Thus, the crystal grains of thefifth to eighth copper alloy materials are refined aftermelt-solidification so as to further improve the characteristics thatthe first to fourth copper alloy materials originally have and so as toensure a high castability. Specifically, the fifth to eighth copperalloy materials respectively have the same or substantially the samecomposition (constituted of the same elements in the same proportionsexcept the balance being Zn) as the first to fourth copper alloymaterials (referred to as copper alloy materials before improvement forthe comparison with the fifth to eighth copper alloy materials), exceptfor containing Zr and P. Each of the fifth to eighth copper alloymaterials is modified so that its macroscopic or microscopic averagegrain size is reduced by ¼ or less (preferably 1/10 or less, morepreferably 1/25 or less) after melt-solidification, by adding Zr and Ptogether. In order to modify the cooper alloy material more effectively,the Sn content [Sn], Zr content [Zr], and P content [P] in terms of mass% of the fifth to eighth copper alloy materials preferably satisfyZ1=0.5 to 150 (preferably Z1=0.8 to 50, more preferably Z1=1.5 to 15,most preferably Z1=2.0 to 12), Z2=1 to 3000 (preferably Z2=15 to 1000,more preferably Z2=30 to 500, most preferably Z2=40 to 300), and Z3=0.2to 250 (preferably Z3=3 to 160, more preferably Z3=5 to 90, mostpreferably Z3=8 to 60), wherein Z1=[P]/[Zr], Z2=[Sn]/[Zr], andZ3=[Sn]/[P]. In addition, the total area ratio of the γ and δ phases inthe phase structure is preferably 0 to 10% (more preferably 0 to 5%,still more preferably 0 to 3%). Optimally, the γ phase is in a boundarystate where it may be formed or not; hence, it is most preferable thatthe area ratio of the γ phase be enormously close to 0%. Optimally, theβ phase is not produced, or if produced, its area ratio should belimited to 5% or less. Preferably, the fifth to eighth copper alloymaterials each result in a crystal structure whose dendritic network isbroken after melt-solidification, and more preferably thetwo-dimensional crystal grain structure is in a circular form or asimilar form after melt-solidification. In order to refine the crystalgrains during melt-solidification, it is important to take into accountthe cooling speed during melt-solidification. For example, if thecooling speed is 0.05° C./s or less, the rate of dendrite growth becomeshigher than that of crystal nucleation, so that the crystal nucleationis canceled by the dendrite growth. Consequently, the crystal grainscannot be refined effectively. In order to produce fine circular orsimilar crystal grains, it is preferable that the cooling speed duringmelt-solidification be taken into account. In general, a preferredcooling speed is 0.1° C./s or more (more preferably 0.3° C./s or more).The crystal grain size, crystal structure, and two-dimensional crystalgrain structure after melt-solidification refer to those aftermelt-solidification performed by casting or welding the fifth to eighthcopper alloy materials, without deformation processing, such asextrusion or rolling, or heat treatment.

Any of the fifth to eighth copper alloy materials may contain inevitableimpurities. If the copper alloy material contains Fe and/or Ni asinevitable impurities (except for the seventh and eighth copper alloymaterials containing Ni), their contents are each preferably 0.5 mass %or less. If the content of these impurities is high, they consume Zr andP (which contribute to crystal grain refining), to inhibit the crystalgrain refining, disadvantageously. It is therefore preferable that if Feand/or Ni is contained as impurities, their contents are each limited to0.5 mass % or less (more preferably 0.2 mass % or less, still morepreferably 0.1 mass % or less, most preferably 0.05 mass % or less).

The first to fourth copper alloy materials are generally provided inplastic-processed form prepared by plastic processing (extrusion orrolling, and physical deformation processing that may be performedsubsequent to the extrusion or rolling, such as wiredrawing, drawing, orrolling) in which large casting material (for example, billet or ingot)obtained by metal mold casting is formed into wires or bars. Forexample, such plastic-processed materials include primaryplastic-processed wires or bars obtained by extruding or rolling acasting material and secondary plastic-processed wires or bars obtainedby subjecting the primary plastic-processed wires or bars towiredrawing, drawing, or rolling. The fifth to eighth copper alloymaterials are provided in combined-processed wire or bar form preparedby casting, such as horizontal continuous casting or upward casting(up-casting), or by subsequently subjecting the cast-processed materialto plastic processing (physical deformation processing, such aswiredrawing). The combined-processed material is obtained by, forexample, wiredrawing, drawing, or rolling of a cast-processed material.In the plastic processing for preparing the plastic-processed materialor the combined-processed material, the following cases can be thoughtof according to the difference between the diameters before and afterprocessing the wires or bars: (1) the same procedure for plasticprocessing is repeated several times (for example, wiredrawing ordrawing is repeated several times); (2) different types of plasticprocessing are combined (for example, a material is extruded, andsubsequently the extruded material is subjected to wiredrawing), and (3)cases (1) and (2) are combined (for example, an extruded material isrepeatedly subjected to wiredrawing several times). In any case of (1)to (3), appropriate heat treatment (annealing) is performed once or morebefore and/or after the plastic processing, as needed. Such heattreatment may be performed in order to enhance the antifouling propertyor antibiotic properties (bactericidal and sterilizing properties) ofthe copper alloy material.

In the first to eighth copper alloy materials, Cu and Zn are necessaryfor controlling leaching of the copper ions from the copper alloymaterial under seawater, ensuring strength sufficient for cultivationnets or the like, and preventing the material from being worn out bycontact with waves and fish and contact with other parts of thematerial. These effects cannot be sufficiently produced if the Cucontent is less than 62 mass %. The corrosion resistance also becomespoor. Also, a Cu content of more than 91 mass % cannot achievesufficient seawater resistance, and the strength and the wear resistancebecome poor. In order for Cu and Zn to ensure sufficient strength,corrosion resistance, and seawater resistance, the Cu content should beset at 62 to 91 mass %. For setting the Cu content, the proportions tothe other constituent elements must be considered. In particular, thelower limit and upper limit of the Cu content should be set in view ofthe following considerations, but depending on the ratio of the Sncontent to the Zn content. The lower limit should be set so that, first,a more stable corrosion resistance and erosion-corrosion resistance canbe ensured and, second, the primary crystal is in an α phase duringmelt-solidification and involved in peritectic reaction so as to allowgrain refining during melt-solidification. The upper limit should be setso that, first, a higher strength and wear resistance are ensured and,second, the copper alloy material has such a low hot deformationresistance as to be extruded through a small diameter, from theviewpoint of cost reduction, if it is prepared by hot extrusion. Third,the upper limit should be set so as to allow peritectic reaction forfurther grain refining during melt-solidification. In view of theseconsiderations, the Cu content should be set at 62 to 91 mass %,preferably 63 to 82 mass %, and most preferably 64 to 77 mass %. Zn, aswell as Cu and Sn, is one of the primary constituents of the(Cu—Zn—Sn-based) alloy composition of the first to eighth copper alloymaterials. The Zn helps the occurrence of a peritectic reaction, whichrefines the crystal grains of the alloy during melt-solidification,reduces the stacking fault energy of the alloy to enhance theflowability of the molten metal and accelerate the reduction of itsmelting point in a wire forming step, and enhances the corrosionresistance (particularly erosion-corrosion resistance) and mechanicalstrength (tensile strength, proof stress, impact strength, wearresistance, fatigue strength, etc.) of the resulting wires. Inparticularly the fifth to eighth copper alloy materials, Zn alsoaccelerates crystal grain refining during melt-solidification andprevents Zr from being lost by oxidation.

In the first to eighth copper alloy materials, Sn is mainly intended toenhance the corrosion resistance (such as seawater resistance). Theaddition of 0.01 mass % or more of Sn enhances the corrosion resistance,the erosion-corrosion resistance, the wear resistance, and the strength.However, a Sn content of more than 4 mass % does not produce theseeffects to an extent according to the content. On the contrary, such aSn content results in a degraded castability (causing cracks, shrinkagecavities, and porous shrinkage cavities), thus degrading the hotworkability and cold workability. For use of the copper alloy materialfor fish cultivation nets, by setting the Sn content at 0.1 mass % ormore, the strength of the alloy material of the cultivation nets can beincreased. A higher Sn content not only enhances the seawater resistanceand erosion-corrosion resistance of the cultivation net material, butalso prevents the wires from being worn out by waves or the likeeffectively to enhance the wear resistance to rubbing by fish or rubbingagainst each other. This is because Sn-rich corrosion-resistant coatingsare formed over the surfaces of the wires and the coatings prevent fishfrom coming into direct contact with the wires, and the wires from beingworn out by the contact with seawater flowing at a high speed. Inaddition, Sn expands the range of composition in which peritecticreaction (refining crystal grains effectively duringmelt-solidification) can occur. As the Sn content is increased, theperitectic reaction can occur in compositions having a wider range of Cucontent in practice. Accordingly, the Sn content is preferably 0.6 mass% or more, and most preferably 0.8 mass % or more. In contrast, a Sncontent of more than 4 mass % allows the γ or δ phase, which is a hardphase having a higher Sn content than the parent phase (a phase), to benotably produced at an area ratio of 10% or more, but depending on theCu and Zn contents. Consequently, the material can become easy to breakduring wiredrawing, and the γ phase can be selectively corroded toreduce the seawater resistance. If the net repeatedly suffers strongstresses, the net may result in fatigue fracture. Thus, an excessivelyhigh Sn content causes Sn to segregate significantly to degrade the hotductility and the cold workability and ductility, but depending on theCu and Zn contents. Furthermore, the range of solidification temperatureexpands according to the increase of the Sn content, and consequentlythe castability is degraded. In view of these considerations, the Sncontent should be set at 0.01 to 4 mass %, preferably 0.1 to 3 mass %,more preferably 0.6 to 3 mass %, and most preferably 0.8 to 2.5 mass %so as to establish an appropriate ratio of the γ phase to the δ phase.In order to form the γ phase and the δ phase at a ratio in the aboverange and melt and disperse the Sn uniformly as much as possible, it ispreferable that the alloy composition be adjusted so that thecompositional value Y9=0.06[Cu]−[Sn] derived from the Cu and Sn contentsis 1 to 4.5 (preferably 1.5 to 4.2, more preferably 2 to 3.8, mostpreferably 2.5 to 3.5).

In the fifth to eighth copper alloy materials, Zr and P are added inorder to refine the crystal grains of the resulting copper alloy,particularly the crystal grains after melt-solidification. Althoughsingly used Zr or P can only slightly reduce the crystal grain size ofthe alloy, as well as other common additive elements, a combined use ofZr and P can refine the crystal grains remarkably effectively. Thiseffect of refining the crystal grains is exerted when the Zr content is0.0008 mass % or more, preferably 0.002 mass % or more, more preferably0.004 mass % or more, and most preferably 0.006 mass % or more, and whenthe P content is 0.01 mass % or more, preferably 0.02 mass % or more,more preferably 0.025 mass % or more, and most preferably 0.035 mass %or more. However, if the Zr content reaches 0.045 mass % or the Pcontent reaches 0.25 mass %, the effect of combined use of Zr and P incrystal grain refining is completely saturated regardless of otherconstituents and their contents. Hence, the Zr and the P content capableof exerting this effect effectively are 0.045 mass % or less and 0.25mass % or less, respectively. Such low Zr and P contents set in theabove ranges do not inhibit the characteristics derived from the otherconstituents of the resulting alloy. On the contrary, such Zr and Pcontents allow crystal grain refining, so that Sn can be uniformlydispersed without forming a series of regions having a high content ofsegregated Sn. Consequently, cast cracks can be prevented and healthycast with a low microporosity can be produced. Furthermore, theworkability in cold drawing and cold extraction can be enhanced and,thus, the characteristics of the resulting alloy can be enhanced. Inother words, by adding small amounts of Zr and P, the Cu—Zn—Sn-basedcopper alloys can be modified so as to have a smaller crystal grain sizethan their corresponding alloys containing the same constituents exceptZr and P (like, for example, the alloy of the fifth copper alloymaterial corresponding to the first copper alloy material, the alloy ofthe sixth copper alloy material corresponding to the second copper alloymaterial, the alloy of the seventh copper alloy material correspondingto the third copper alloy material, and the alloy of the eighth copperalloy material corresponding to the fourth copper alloy material) whileensuring characteristics superior or equivalent to their originalcharacteristics.

Zr has an extremely high affinity for oxygen. Accordingly, if rawmaterials are melted in air or if scraps (waste cultivation nets) areused as the raw materials, Zr is liable to form oxides or sulfides.Addition of an excessive amount of Zr increases the viscosity of moltenmetal. The molten metal traps oxides or sulfides during casting, andcast defects thus occur which easily result in blowholes ormicroporosities. In order to prevent this, melting and casting can beperformed in a vacuum or a complete inert gas atmosphere. This howeverlimits the versatility of the process and increases the costs of copperalloys containing Zr as a grain-refining element. In view of theseconsiderations, the Zr content is preferably set so as not to formoxides or sulfides. Such a Zr content is preferably 0.0290 mass % orless, more preferably 0.0240 mass % or less, and most preferably 0.0190mass % or less. A Zr content in these ranges reduces the formation ofzirconium oxides or sulfides and thus makes it possible to produce ahealthy copper alloy material constituted of fine crystal grains, evenif the fifth to eighth copper alloy materials are reused and melted inair.

Accordingly, the Zr content should be 0.0008 to 0.045 mass %, preferably0.002 to 0.029 mass %, more preferably 0.004 to 0.024 mass %, and mostpreferably 0.006 to 0.019 mass %.

In the fifth to eighth copper alloy materials, P is added in combinationwith Zr, as described above, to refine the crystal grains. P, however,affects the seawater resistance, corrosion resistance, castability, andcold and hot ductility. In view of the effects of P on the seawaterresistance, the corrosion resistance, the castability, and the cold andhot ductility in addition to the effect of combined use of P and Zr inrefining the crystal grains, the P content should be set at 0.01 to 0.25mass %, preferably 0.02 to 0.18 mass %, more preferably 0.025 to 0.15mass %, and most preferably 0.035 to 0.12 mass %.

The present invention is also directed to a method for manufacturingcopper alloy materials, particularly the fifth to eighth copper alloymaterials. In the method, Zr in copper alloy form is added immediatelybefore pouring in a casting step so that addition of oxides or sulfidesof Zr can be prevented in this step. In the casting step of the castingmaterial used in the manufacture of the fifth to eighth copper alloymaterials, it is preferable that Zr be added in a form of granular orthin-plate intermediate alloy (copper alloy) immediately before pouringso that addition of Zr in form of oxide or sulfide is prevented. SinceZr is easy to oxidize, as described above, it may be advantageous that,in casting, to add Zr immediately before pouring. In this instance, theZr is preferably in an intermediate alloy form of granules (grain size:about 2 to 50 mm) or thin plate (thickness: about 1 to 10 mm) having alow melting point close to the melting point of the targeted copperalloy and containing many types of constituents (for example, in a formof Cu—Zr or Cu—Zn—Zr alloy containing mainly 0.5 to 65 mass % of Zr, and0.1 to 5 mass % each of at least one element selected from the groupconsisting of P, Mg, Al, Sn, Mn, and B), because the melting point of Zris 800 to 1000° C. higher than that of the targeted copper alloy. Inparticular, in order to reduce the melting point so that the Zr can beeasily melted, and in order to prevent Zr from being lost by oxidation,a Cu—Zn—Zr-based alloy containing 0.2 to 35 mass % of Zr and 15 to 50mass % of Zn (more preferably 1 to 15 mass % of Zr and 25 to 45 mass %of Zn) is preferably used. Zr impairs the electrical and thermalconductivities, which are inherent characteristics of copper alloys, butdepending on the proportion to P used in combination with Zr. However,if the content of Zr in a form of non-oxide or non-sulfide is 0.045 mass% or less (particularly 0.019 mass % or less), the electrical andthermal conductivities are hardly reduced by addition of Zr. Even if theelectrical or thermal conductivity is reduced, the degree of thereduction is very small in comparison with when Zr is not added.

In the fifth to eighth copper alloy material, single use of Sn singlydoes not much enhance the grain-refining effect. However, Sn used incombination with Zr and P notably exerts the grain-refining effect. Snenhances the mechanical properties (for example, strength), thecorrosion resistance, and the wear resistance. Besides, Sn breaksdendrite arms, or expands the possible ranges of contents of Cu and Zn,which are involved in peritectic reaction, to help peritectic reactioneffectively. Sn thus helps the granulation or refining of the crystalgrains effectively, and this function of Sn is notably exertedparticularly in the presence of Zr (and P). The γ phase produced byadding Sn hinders the growth of crystal grains aftermelt-solidification, thus contributing to the grain refining of thecrystal grains. γ Phases are formed from regions having a high Sncontent. Since the regions having a high Sn content are uniformly andfinely dispersed in the stage of melt-solidification, the resulting γphases are also finely dispersed, and consequently hinder the growth ofα crystal grains at high temperatures after solidification. The finedispersion of the γ phase leads to a high corrosion resistance and wearresistance. It is therefore preferable that, in order to produce theeffect of the combined use of Zr and P in refining the crystal grains ofthe fifth to eighth copper alloy materials, the Zr and the P content beset with consideration of their relationship and the relationship withthe Sn content. Specifically, their proportions Z1 (=[P]/[Zr]), Z2(=[Sn]/[Zr]), and Z3 (=[Sn]/[P]) are preferably set in the above ranges.Among these proportions, Z1 or the proportion of P to Zr is important inrefining the crystal grains. If the proportion Z1 is in the above range(Z1=0.5 to 150), the rate of crystal nucleation is higher than that ofcrystal growth during melt-solidification. Consequently, even the grainsof a melt-solidified product can be refined to an extent equivalent tothe grains of hot-worked material or recrystallized material. Inparticular, by setting the proportion Z1 of P to Zr at 0.8 to 50, thedegree of crystal grain refining can be improved. A Z1 value of 1.5 to15 further improves the degree of crystal grain refining; and a Z1 valueof 2.0 to 12 still further improves the degree.

The element X1 (at least one element selected from the group consistingof As, Sb, Mg, and P) contained in the second and fourth copper alloymaterials and the element X3 (at least one element selected from thegroup consisting of As, Sb, and Mg) contained in the sixth and eighthcopper alloy materials are mainly intended to enhance the corrosionresistance (particularly dezincification corrosion resistance). Theaddition of 0.02 mass % or more of Sb or As enhances the seawaterresistance and the corrosion resistance. In order for these elements toproduce the effect of enhancing the corrosion resistance notably, Sb orAs is added preferably in an amount of 0.03 mass % or more. However, aSb or As content of more than 0.25 mass % does not produce this effectto an extent according to the content and reduces the ductility (ease ofwiredrawing) of the material. In view of the decrease of ductility, theSb content and the As content each should be set at 0.25 mass % or less.In addition, in view of the hot workability and the cold workability,their contents are each preferably set at 0.12 mass % or less. Hence,the As and the Sb content each should be 0.02 to 0.25 mass %, andpreferably 0.03 to 0.12 mass %.

The raw materials of the copper alloy often include scraps (waste heatexchanger tubes), and the scraps often contain S (sulfur). In use ofS-containing scraps as raw materials of an alloy, Mg being element X1 orX3 enhances the flowability of molten metal in casting, as well asenhancing the corrosion resistance. Mg can remove constituent S byforming MgS, which has a less negative effect than S. Since the MgS doesnot adversely affect the corrosion resistance even if it remains in theresulting alloy, Mg can prevent the degradation of the corrosionresistance resulting from the presence of S in the raw material,effectively. Constituent S in the raw material is liable to be presentin grain boundaries and consequently may corrode the grain boundaries.The addition of Mg can prevent the grain boundary corrosion effectively.In order to produce such an effect, the Mg content should be set at0.001 to 0.2 mass %, preferably 0.002 to 0.15 mass %, and morepreferably 0.005 to 0.1 mass %. In the sixth and eighth copper alloymaterials, the molten metal may have such a high S content as S consumesZr, disadvantageously. By adding 0.001 mass % or more of Mg to themolten metal before adding Zr, the constituent S in the molten metal isremoved by forming MgS. Thus, the above problem does not occur. However,if the Mg content is more than 0.2 mass %, Mg is oxidized, as in thecase of Zr, to increase the viscosity in melting. Consequently, forexample, trapped oxides may bring about a cast defect. In the case whereMg is used as X3, therefore, the Mg content is set in the above range.

P used as X1 contributes to the increase of seawater resistivity andincreases the flowability of the molten metal. These effects are exertedat a P content of 0.01 mass % or more, preferably 0.018 mass % or more,more preferably 0.15 mass % or more, and most preferably 0.12 mass % ormore. However, an excessive P may adversely affect the cold and hotductilities and the castability. In view of this, the P content shouldbe set at 0.25 mass % or less, preferably 0.18 mass % or less, morepreferably 0.15 mass % or less, and most preferably 0.12 mass % or less.Hence, the content of P used as X1 should be 0.01 to 0.25 mass %,preferably 0.02 to 0.018 mass %, more preferably 0.025 to 0.15 mass %,and most preferably 0.035 to 0.12 mass %, as in the case of the P usedas a necessary constituent in the fifth to eighth copper alloymaterials.

In the third and fourth copper alloy materials or the seventh and eighthcopper alloy materials, element X2 or X4, which is at least one elementselected from the group consisting of Al, Si, Mn, and Ni, is added inorder to mainly enhance the strength, the flowability, theerosion-corrosion resistance at a high flow rate, and the wearresistance. In particular, the addition of the element X2 or X4 isadvantageous when the copper alloy material is used as wires or barsforming seawater netted structures (for example, fish cultivation nets).By adding the element X2 or X4, the wear and tear of the wires or barscan be prevented effectively even under harsh conditions (when thecultivation net is placed in an offing whose environmental conditionsare strongly influenced by waves, or when the net is used forcultivation of large, fast migratory fish that hits the net to give it alarge impact, such as yellowtail or tuna). For example, a seawaternetted structure formed of a large number of wires (particularly fishcultivation net) can be worn out or torn rapidly by seawater or wavesrunning at a high speed, by contact with or hit by cultured fish, or byrubbing of the wires against each other. Al and Si each form a strong,corrosion-resistant Al—Sn or Si—Sn coating over the surface of thewires. The coating enhances the wear resistance of the wires to preventthe wear and tear of the wires as much as possible. A combination of Mnand Sn also form a corrosion-resistant coating. Specifically, Mn canform an intermetallic compound by combined use with Si and furtherenhance the wear resistance of the wires; hence, Mn mainly has theeffect of forming an intermetallic compound preventing the wear and tearof the wires. X2 enhances the flowability of molten metal in casting, aswell as enhancing the wear resistance. In order for X2 to produce theseeffects, 0.02 mass % or more of Al or Si should be added (for Al, 0.05mass % or more is preferable and 0.1 mass % or more is much preferable;for Si, 0.1 mass % or more is preferable). If Mn is added, the Mncontent should be 0.05 mass % or more (preferably 0.2 mass % or more).However, if more than 1.5 mass % of Mn or Al is added, the ductility isdegraded to adversely affect wiredrawing. In particular, when theresulting cultivation net is used under the above-described harshconditions, the materials of the net can be cracked or broken byrepeated bending or the like. In order to prevent the degradation ofductility and the crack or breakage resulting from repeated bending,effectively, the Si content should be 1.9 mass % or less and the Al andMn contents each should be 1.5 mass % or less (for Al, 1.2 mass % orless is preferable and 1 mass % or less is more preferable; for Si andMn, 1 mass % or less is preferable). If Al is used as X2 or X4, it canform a dense oxide coating over the surface of the copper alloy byappropriate heat treatment (annealing), thus further enhancing thedurability. In this instance, the Al content is preferably set at 0.1 to1 mass %, and the heat treatment is preferably performed at a lowtemperature for a long time. Specifically, the heat treatment ispreferably performed at a temperature of 400 to 470° C. for 30 minutesto 8 hours. The Ni content should be set at 0.005 mass % or more fromthe viewpoint of enhancing the corrosion resistance. In view of theinfluence of Ni on the hot workability and the consumption (inhibitingcrystal grain refining) by Ni of Zr and P, which are useful in refiningcrystal grains in the seventh and eighth copper alloy materials, the Nicontent is preferably 0.5 mass % or less (more preferably 0.1 mass % orless).

In the first to eighth copper alloy materials, in order to ensure theresulting netted structure (for example, a fish cultivation net) hascharacteristics (seawater resistance, wear resistance, ductility,strength, etc.) sufficient to be used under or in contact with seawater,the alloy material should have the above-described composition andinclude α, γ, and δ phases at a total area ratio of 95 to 100%(preferably 98 to 100%, more preferably 99.5 to 100%). An excessive γand/or δ phase easily causes the alloy material to break duringwiredrawing, and particularly brings the γ phase into selectivecorrosion to degrade the seawater resistance. Although the γ phaseenhances the wear resistance and the erosion-corrosion resistance andthe δ phase enhances the erosion-corrosion resistance, the presence ofthe γ and/or δ phase degrades the ductility. In order to bring thestrength, wear resistance, and ductility into balance without breakingby wiredrawing or degrading the seawater resistance, the alloy materialhas the above-described composition and, preferably, the total arearatio of the γ and δ phases is set at 0 to 10% (preferably 0 to 5%, morepreferably 0 to 3%). The phase structure may be occupied by 95 to 100%of α phase (preferably 98 to 100%, more preferably 99.5 to 100%),containing neither γ nor δ phase (for example, the phase structure isessentially composed of only the α phase, or the α and β phases),depending on the process of plastic processing for manufacturing thefirst to eighth copper alloy materials. If the γ phase is present, it ispreferable that the γ phase be fractured (preferably, into ellipticalfragments with a length of 0.2 mm or less) from the viewpoint ofminimizing the selective corrosion by the γ phase and the degradation ofductility. Since a series of β phase fragments reduces the seawaterresistance, the β phase should not be formed in view of the seawaterresistance. However, the formation of the β phase enhances the hotworkability (particularly extrusion workability). Accordingly, thecontent (area ratio) of the β phase is preferably 5% or less (preferably2% or less, more preferably 0.5% or less). If the seawater resistance isparticularly important, it is preferable that the phase structure do notinclude the β phase. If any of the first to eighth copper alloymaterials has a phase structure including the γ phase and/or the βphase, the copper alloy material is preferably subjected to appropriateheat treatment (for example, annealing at a temperature of 450 to 600°C. for 0.5 to 8 hours) to fracture the γ and β phases into sphericalfragments. By fracturing the γ and β phases into spherical fragments,the negative effect resulting from the formation of the γ and β phasescan be eliminated as much as possible. In the presence of fracturedspherical γ phase fragments, for example, the degradation of ductility,which results from the formation of the γ phase, is reduced and the wearresistance is enhanced. The heat treatment is performed by, for example,homogenization annealing (heat treatment at a temperature of 450 to 600°C. and cooling to 450° C.) of the copper alloy material or itsintermediate product, and preferably by subsequent finish annealing at atemperature of 400 to 470° C. Since the combined use of Zr and P refinescrystal grains to fracture the γ phase into spherical fragmentsinevitably, the γ phase can be more uniformly dispersed.

In order to provide the above-described phase structure in the first toeighth copper alloy materials, the Sn content should be controlledaccording to the proportions to the Cu and the Zn content. Specifically,the contents of the constituent elements should be set so that thecompositional values Y1 to Y8 are each in the range of 62 to 90(preferably 62.5 to 81, more preferably 63 to 76, most preferably 64 to74). The lower limits of Y1 to Y8 are set as described above so that theproportions of the main constituents Cu, Sn, and Zn ensure a superiorseawater resistance, erosion-corrosion resistance, and wear resistance.In addition, in view of the cold-drawability, ductility, corrosionresistance and castability associated with the γ and/or δ phase, theupper limits of Y1 to Y8 should be set as described above. In order toensure these properties, the Sn content is varied depending on the Cucontent. In the fifth to eighth copper alloy materials, Zr and P areadded mainly for crystal grain refining. If the first to fourth copperalloy materials, which do not contain such grain-refining elements, areproduced in wire or thin bar by hot extrusion, it is preferable that thedeformation resistance in the extrusion be reduced in view of cost. Inorder to reduce the deformation resistance as much as possible, it ispreferable that the Cu content be set at 63.5 to 68 mass % (morepreferably 64 to 67 mass %) and that the compositions of the alloys beset so that Y1 to Y8 satisfy the above ranges.

The fifth to eighth copper alloy materials achieve refined crystalgrains by adding Zr and P, and have an average grain size of 0.2 mm orless (preferably 0.1 mm or less, most preferably 0.06 mm or less) aftermelt-solidification. The materials can be produced in wire or bar formby continuous casting, such as upward casting (up-casting), and theresulting wire or bar can be put into practical use. Also, the number ofsteps in the plastic processing for preparing plastic-processed orcombination-processed wires or bars can be reduced, and thus themanufacturing costs can be greatly reduced. If the crystal grains arenot refined, repeated heat treatments (including homogenizationannealing) are required to remove the dendrite structure peculiar tocast metal and segregated Sn and to fracture the γ phase into sphericalfragments. Also, coarse crystal grains degrade the surface state of theresulting material. This easily causes cracks during plastic processing(wiredrawing or drawing) for forming wires or bars, in association withthe segregation of Sn. Thus, the number of the steps of plasticprocessing for preparing targeted plastic-processed wires or bars issignificantly increased. In contrast, if the crystal grains are refinedas described above, homogenization annealing is not necessary becausesegregation is microscopic. Consequently, the number of the steps ofplastic processing and heat treatment for forming plastic-processedproducts (particularly wires or thin bars) being the fifth to eighthcopper alloy materials can be greatly reduced. For example, by applyingwiredrawing or drawing once (wiredrawing twice including finishwiredrawing for adjusting the temper) and heat treatment (annealing)once to a casting material or a cast-processed material, the resultingfifth to eighth copper alloy materials can have high quality and can beused suitably for cultivation nets or the like. For example, in theformation of wires by wiredrawing, since crystal grain refining enhancesthe ductility and reduces asperities at the surface of the copper alloymaterial, breakage during wiredrawing can be prevented. For facing (suchas healing) of the surface of the copper alloy material, the cuttingallowance can be small. In the case where the γ and/or δ phaseprecipitates, the phase is present in the grain boundary, and thesmaller the crystal grains are, the shorter the phase length is.Accordingly, a special step for fracturing the γ and/or δ phase is notrequired, or if required, the step can be kept at minimum. Thus thenumber of steps in the manufacturing process can be greatly reduced, andaccordingly the manufacturing costs can be reduced as much as possible.It goes without saying that wires or bars from which segregation is noteliminated do not have satisfactory characteristics, including corrosionresistance and mechanical properties.

Since the fifth to eighth copper alloy materials achieve refined crystalgrains, as described above, the Sn and the Cu content can be increasedwithout segregation of Sn resulting from a high Sn content, ordegradation of extrusion workability due to the increase of hotdeformation resistance resulting from a high Cu content. Specifically,while a high Sn content of 1 to 1.5 mass % or more promises to increasethe corrosion resistance or other properties greatly, the high contentof Sn brings about segregation so significantly as to easily formcracks, shrinkage cavities, blowholes, or microporosities duringmelt-solidification, and besides cracks during hot working. However, ifcrystal grains are refined during melt-solidification, these problems donot occur and the Sn content therefore can be increased to furtherenhance the seawater resistance. A high Cu content (Cu content: 68 mass% or more) increases the hot deformation resistance to degrade the hotworkability notably, particularly extrusion workability. However, if thecrystal grains are refined, this problem does not occur and thedegradation of hot workability can be prevented even if the Cu contentis high.

In the fifth to eighth copper alloy materials, the addition of Zr and Pis performed to refine the crystal grains, but does not impair theinherent characteristics of the copper alloy. The crystal grain refiningby addition of Zr and P ensures characteristics superior or equivalentto the original characteristics of the corresponding copper alloymaterial containing the same constituents except the grain-refiningelements Zr and P, as described above. In order to reduce the averagegrain size after melt-solidification to the above-described level, theratio Z1 of P to Zr, which are grain-refining elements, and the ratiosof Sn to Zr and Sn to P, namely Z2 and Z3, are set in the above ranges,in addition to setting the Sn content and other contents so that thecopper alloy material has a composition and phase structure satisfyingthe compositional values Y1, Y3, and Y4, as described above.

According to a second aspect of the present invention, a nettedstructure used in seawater is provided which is formed of any one of thefirst to eighth copper alloy materials and which leads to, for example,practical copper nets having superior characteristics for fishcultivation (antifouling property, bactericidal and sterilizingproperties, etc.).

The seawater netted structure of the present invention is formed ofcopper alloy wires or bars being any one of the first to eighthmaterials. The netted structure is formed of plastic-processed,cast-processed, or combination-processed wires or bars in a wire nettingor grid.

Preferably, the seawater netted structure of the present invention ismade by forming wires being any one of the first to fourth copper alloymaterials or the fifth to eighth copper alloy materials into wirenetting. Preferably, the netted structure has a rhombically netted formmade by arranging a large number of waved wires in parallel such thatthe adjacent wires are entwined with each other at their curvedportions. The seawater netted structure is mainly used as a fishcultivation net. The cultivation net has a ring-shaped reinforcing framealong the lower edge of the net. The reinforcing frame maintains theshape of the lower edge of the net, and it is preferably spread withdownward tension. By maintaining the shape by the reinforcing frame andby applying such tension, the wires can be prevented as much as possiblefrom rubbing against each other at the entwined portions. Thereinforcing frame is preferably formed by a pipe made of a copper alloyhaving the same composition as the material of the net (wires being anyone of the first to eighth copper alloy materials).

In addition to the cultivation net made of any one of the first tofourth or the fifth to eighth copper alloy materials (wires), theseawater netted structure of the present invention may be a seawaterintake or the like formed of any one of the bar-shaped first to fourthor fifth to eighth copper alloy materials (bars) in a grid manner bywelding or the like.

If the wire (netting wire) used for the fish cultivation net or the likeis any one of the first to fourth copper alloy materials(plastic-processed materials), the wire is prepared by, for example,repeatedly drawing and annealing a wire (diameter: 10 to 25 mm) formedby extrusion of a casting material (billet, ingot, or the like) into adiameter of 3 to 4 mm. In this instance, this wiredrawing is repeatedseveral times depending on the difference in diameter between theextruded wire and the netting wire (percentage of wiredrawing). If thenetting wire is any one of the fifth to eighth copper alloy materials,the netting wire is formed by, for example, drawing a cast wire(diameter: 5 to 10 mm) formed by horizontal continuous casting or upwardcasting (up-casting) into a diameter of 3 to 4 mm and subsequentlyannealing once or twice. The cast-processed wire formed by horizontalcontinuous casting or upward casting (up-casting) still containssegregated Sn, and accordingly it may not be suitable for cultivationnets. However, it can be suitably used for seawater netted structuresother than the cultivation nets.

Advantages

The first to eighth copper alloy materials have extremely superiorseawater resistance and durability to the known copper alloy materials.In use for a seawater netted structure used under or in contact withseawater, such as a fish cultivation net, the copper alloy materials canprevent the corrosion and the wear and tear of the netted structure byseawater, waves, and cultured fish as much as possible, therebyincreasing the lifetime of the structure. Accordingly, these copperalloy materials can extend the application of the seawater nettedstructure to the fields where it has not been used for the reason of thetotal cost including the lifetime of the alloy, using the superiorcharacteristics (antibiotic property, antifouling property, etc.) of thecopper alloy to those of other metals effectively.

In particular in the fifth to eighth copper alloy materials, the crystalgrains are refined after melt-solidification, that is, grain refining inthe cast structure is achieved in terms of not only macroscopicstructure but also microscopic structure, by adding small amounts of Zrand P. The above characteristics of these copper alloy materials can beimproved more than those of not only the known copper alloy material butalso the first to fourth copper alloy materials (copper alloy materialsbefore improvement) containing the same constituent elements except Zror P. Furthermore, since the crystal grains are refined during casting,the castability can be greatly enhanced and the plastic workability ofthe copper alloy can be improved. Thus, the fifth to eighth copper alloymaterials allow satisfactory plastic processing, such as extrusion orwiredrawing, after casting.

In the seawater netted structure, particularly a fish cultivation net,made of any one of the first to eighth copper alloy materials, thedurability, which is a fault in the known copper nets, can be greatlyenhanced to the extent that the net can be used in practice in view ofthe total cost without adversely affecting advantages of the knowncopper nets. By using the fish cultivation net made of any one of thefirst to eighth copper alloy materials, any type of fish including largemigratory fish can be cultured healthily and economically. Inparticular, for the fish cultivation net or the like made of any one ofthe fifth to eighth copper alloy materials, the material can be preparedonly by about one or two wiredrawing operations (or by a casting processnot requiring even wiredrawing, depending on the conditions orapplication where the seawater netted structure is used) withoutextrusion. Accordingly, the number of steps for such processing can bereduced without a large casting or extrusion system, and thusmanufacturing costs can be greatly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a fish preserve using a fish cultivation netbeing a seawater netted structure according to the present invention.

FIG. 2 is a transverse sectional view taken along line II-II of FIG. 1.

FIG. 3 is a fragmentary enlarged front view of the cultivation net.

FIG. 4 is a transverse sectional view taken along line IV-IV of FIG. 1.

Reference Numerals 1: support frame 2: float 3: fish cultivation net(seawater netted structure) 3a: periphery 3b: bottom 4: reinforcingframe 4a: straight pipe 4b: L-shaped pipe 5: surface of the sea 6:netting wire (wire) 6a: curved portion (entwined portion)

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a front view of a fish preserve using a fish cultivation netbeing a seawater netted structure according to the present invention,and FIG. 2 is a transverse sectional view taken along line II-II ofFIG. 1. FIG. 3 is a fragmentary enlarged front view of the cultivationnet, and FIG. 4 is a transverse sectional view taken along line IV-IV ofFIG. 1.

As shown in FIG. 1, the fish preserve includes a support frame 1, aplurality of floats 2 attached to the support frame 1, and a fishcultivation net 3 hanging from the support frame 1. A reinforcing frame4 is also attached to the lower edge of the cultivation net 3.

The support frame 1 is formed of a metal (for example, iron) square bar,plate, pipe, or the like in a square or rectangular frame form. Thesupport frame 1 doubles as a foothold for cultivation work. The innerperiphery of the support frame 1 has an attachment with which the upperedge of the cultivation net 3 is held. The floats 2 are made of expandedpolystyrene and attached to the bottom surface of the support frame 1along the upper edge periphery of the cultivation net 3 in a rectangularring manner. The floats 2 hold the fish preserve in such a manner as tofloat the support frame 1 on the surface 5 of the sea.

The cultivation net 3, which is formed of copper alloy netting wires 6with a known net forming machine (metal netting machine) used formanufacturing iron nets, includes a square or rectangular tube-likeperiphery 3 a whose upper edge is joined to the attachment provided atthe inner periphery of the support frame 1 with wire ropes or the like,and a square or rectangular bottom 3 b closing the lower edge, as shownin FIGS. 1 and 2. Specifically, the cultivation net 3 has a rhombicallynetted structure made by arranging a large number of waved netting wires6 in parallel such that the curved portions 6 a of each netting wire 6are entwined with the curved portions 6 a of the adjacent netting wires6, as shown in FIG. 3. Any one of the first to fourth copper alloymaterials (for example, plastic-processed material A in Example 1) orfifth to eighth copper alloy materials (for example,combination-processed material B (or cast-processed material) in Example2) is used as the netting wire 6. The shape (lengths of the sides of theperiphery 3 a, dimensions of the mesh S (see FIG. 3), etc.) of thecultivation net 3 is selected according to the installation site, thetype of cultured fish, and the culturing conditions.

The reinforcing frame 4 has a square or rectangular ring structureformed by connecting four straight pipes 4 a with four L-shaped pipes 4b, as shown in FIG. 4, and is attached to the lower edge of thecultivation net 3 in such a manner as to surround the bottom 3 b. Thepipes 4 a and 4 b are made of the same copper alloy as the netting wire6. The connection of the straight pipes 4 a to the L-shaped pipes 4 b issuch that they permit relative displacement to some extent in thedirection of their axes so as to be able to follow the deformation ofthe cultivation net 3 caused by, for example, waves.

The reinforcing frame 4 reinforces the lower edge of the cultivation net3 to maintain its shape. The shape of the cultivation net 3 is thusmaintained at both the upper and lower edges by the support frame 1 andthe reinforcing frame 4; hence, the whole shape can be maintainedappropriately without being largely deformed by waves, large migratoryfish, or the like. The reinforcing frame 4 places downward tension onthe periphery 3 a of the cultivation net 3 due to its own weight. Thereinforcing frame 4 thus functions as a tension-applying member (anchor)for reducing the clearances L (see FIG. 3) between the entwined portions6 a of the netting wires 6 of the periphery 3 a of the cultivation net 3to a uniform small size. The weight of the reinforcing frame 4 ispreferably set so as to apply such a tension as the clearance L becomes0.1 to 10 mm (preferably 0.5 to 5 mm).

The rubbing of the netting wires 6 against each other at the entwinedportions 6 a can be prevented effectively by remaining the shape of thefish cultivation net 3 with the support frame 1 and the reinforcingframe 4 and reducing the clearance L with the tension of the reinforcingframe 4. Thus, the wear and tear resulting from the relative movement ofadjacent netting wires 6 can be prevented as much as possible. Thereinforcing frame 4 is used as the occasion arises, but may not be useddepending on the type of cultured fish or the environment where thecultivation net 3 is used.

EXAMPLES

Example 1 prepared plastic-processed materials in wire form (hereinaftercollectively referred to as plastic-processed wires A) havingcompositions shown in Table 1: Nos. 101 to 108, Nos. 201 to 206, Nos.301 to 305, and Nos. 401 to 405. Wires No. 101 to 108 belong to thefirst copper alloy material; wires Nos. 201 to 206 belong to the secondcopper alloy material; wires Nos. 301 to 305 belong to the third copperalloy material; wires Nos. 401 to 405 belong to the fourth copper alloymaterial.

The plastic-processed wires Nos. 101 to 108, Nos. 201 to 206, Nos. 301to 305, and Nos. 401 to 405 were each prepared as follows. First, acylindrical ingot A-1 having the corresponding composition shown inTable 1 was hot extruded into a round bar A-2 of 12 mm in diameter.Specifically, the compositions containing 68 mass % or more of Cu, whichhave high hot deformation resistances, were formed into cylindricalingots A-1 with a diameter of 60 mm and a length of 100 mm, and werethen hot extruded into round bars A-2 at 850° C. The compositionscontaining less than 68 mass % of Cu were formed into cylindrical ingotsA-1 with a diameter of 100 mm and a length of 150 mm, and were then hotextruded into round bars A-2 at 800° C. Then, the round bars A-2 wereeach subjected to cold wiredrawing to form a primary processed wire A-3of 9 mm in diameter. This wiredrawing was performed through the twosteps of: drawing a round bar A-2 into an intermediate wire of 10.2 mmin diameter; and further drawing the intermediate wire into a primaryprocessed wire A-3 of 9 mm in diameter. The primary processed wire A-3was allowed to stand at 550° C. for an hour and then subjected to coldwiredrawing to form a secondary processed wire A-4 of 6 mm in diameter.The secondary processed wire A-4 was further subjected to coldwiredrawing to form a tertiary processed wire A-5 of 4.3 mm in diameter.The tertiary processed wire A-5 was annealed at 480° C. for an hour andthen subjected to cold wiredrawing. Thus, the plastic-processed wire Aof 4 mm in diameter was obtained.

Example 2 prepared combination-processed materials in wire form(hereinafter collectively referred to as combination-processed wires B)having compositions shown in Table 2 or 3: Nos. 501 to 528, Nos. 601 to607, Nos. 701 to 708, and Nos. 801 to 805. Wires Nos. 501 to 528 belongto the fifth copper alloy material; wires Nos. 601 to 607 belong to thesixth copper alloy material; wires No. 701 to No. 708 belong to theseventh copper alloy material; wires Nos. 801 to 805 belong to theeighth copper alloy material.

The combination-processed wires Nos. 501 to 528, Nos. 601 to 607, Nos.701 to 708, and Nos. 801 to 805 were each prepared as follows. First, acasting wire B-1 of 6 mm in diameter having the correspondingcomposition shown in Table 2 or 3 was subjected to continuous casting ata low speed (1 m/minute) with a casting apparatus including a meltingfurnace (ingoting ability: 60 kg) equipped with a horizontal continuouscasting machine. Molding is continuously performed with graphite whileadditive elements were added as needed so as to give a predeterminedcomposition. Then, the casting wire B-1 was subjected to coldwiredrawing to form a primary processed wire B-2 of 4.3 mm in diameter.This wiredrawing was performed through the two steps of: drawing thecasting wire B-1 into an intermediate wire of 5 mm in diameter; andfurther drawing the intermediate wire into the primary processed wireB-2 of 4.3 mm in diameter. The primary processed wire B-2 was annealedat 480° C. for an hour and then subjected to cold wiredrawing. Thus, thecombination-processed wire B of 4 mm in diameter was obtained.

Comparative Example 1 prepared wires Nos. 1001 to 1006 of 4 mm indiameter (hereinafter collectively referred to as first comparativeexample wires C) having compositions shown in Table 4 in the samemanufacturing process as in the case of the plastic-processed wires A ofExample 1. The first comparative example wires C were prepared forcomparison with the first to fourth copper alloy materials. As for wireNo. 1003, a large defect (crack) occurred in the course of forming theprimary-processed wire A-3, and thus no intended wire C was obtained.

Comparative Example 2 prepared combination-processed wires Nos. 2001 to2013 and Nos. 2501 to 2505 of 4 mm in diameter (hereinafter collectivelyreferred to as second comparative example wires D) having compositionsshown in Table 5 in the same manufacturing process as in the case of thecombination-processed wires B of Example 2. The second comparativeexample wires D were prepared for comparison with the fifth to eighthcopper alloy materials. Wires Nos. 2501 to 2505 contain the sameelements as wires Nos. 501 to 505 respectively, except that crystalgrain-refining elements Zr and P were not added. As for wires Nos. 2009and 2011, large defects occurred in the course of forming the primaryprocessed wires B-2. As for wires Nos. 2010, 2012, and 2502 to 2505,large defects occurred in the course of forming the casting wires B-1.Thus, second comparative example wires D for those numbers were notobtained. As for wires Nos. 2001, 2002, 2005, and 2013, although cracksoccurred in their primary processed wires B-2, intended secondcomparative example wires D were obtained because the cracks were not solarge.

The resulting wires A, B, C, and D were subjected to tension tests andbending tests for inspecting the mechanical properties as follows.

The tension test was performed to obtain the tensile strength (N/mm²),elongation (%), and fatigue strength (N/mm²) of the wires A, B, C, and Dwith an Amsler universal tester. The results are shown in Tables 6 to10. On Nos. 1003, 2009, 2010, 2011, 2012, and 2502 to 2505, which didnot achieve intended wires C and D, the tension test and the followingtests were not performed.

For the bending test, each of wires A, B, C, and D extending in thevertical direction was fixed at the midpoint and was repeatedlysubjected to several bending operations until the curved portion wascracked, and thus the durability to repetitive deformation was examined.The single bending operation was performed such that the upper portionfrom the fixed portion was bent in a horizontal direction at a bendradius of 6 mm, then restored to the vertical state, further bent in thereverse horizontal direction, and restored to the vertical state again.The results are shown in Tables 6 to 10.

In addition, wires A, B, C, and D were subjected to the followingseawater resistance tests I to IV and the dezincification corrosionresistance test specified in ISO 6509 to examine the corrosionresistance and the seawater resistance.

In the seawater resistance tests I to IV, erosion-corrosion test wasperformed such that a test solution (30° C.) was jetted at a flow rateof 11 m/s onto test pieces of the wires A, B, C, and D from a nozzlewith a bore of 1.9 mm in the direction perpendicular to the axis of thewires. After a predetermined time T had elapsed, corrosion weight loss(mg/cm²) was measured. The test solution was: 3% salt solution forseawater resistance tests I and II; a mixed solution of CuCl₂.H₂O (0.13g/L) in 3% salt solution for seawater resistance test III; and 3% saltsolution containing glass beads (5 vol. %) with a average diameter of0.115 mm for seawater resistance test IV. The corrosion weight loss wasdefined by the difference per square centimeter (mg/cm²) between theweights of the test piece before test and after jetting the testsolution onto the test piece for a time T. The jetting time was: 96hours for seawater resistance tests I and III; 960 hours for seawaterresistance test II; and 24 hours for seawater resistance test IV. Theresults of seawater resistance tests I to IV are shown in Tables 6 to10.

In the dezincification corrosion resistance test of ISO 6509, testpieces of the wires A, B, C, and D were each fixed to a phenol resinsuch that the exposed surfaces of the test pieces were perpendicular tothe direction of expansion and contraction, and the surfaces of the testpieces were ground with emery papers of up to #1200. Then, test pieceswere ultrasonic-cleaned in pure water, following by drying. The thusobtained corroded test pieces were immersed in 1.0% copper (II) chloridedihydrate (CuCl₂.2H₂O) solution and allowed to stand at 75° C. for 24hours. Then, the test pieces were taken out of the solution and themaximum depth of dezincification corrosion (μm) was measured. Theresults are shown in Tables 6 to 10.

The phase structures of the wires A, B, C, and D were subjected to imageanalysis to measure the area ratios (%) of the α, γ, and δ phases.Specifically, a phase structure image taken at a magnification of 200times by an optical microscope was binarized with an image processingsoftware program “WinROOF” and the area ratio of each phase wasdetermined. The area ratio of each phase was measured in three views andthe average was defined as the area ratio of the corresponding phase.The results, which are shown in Tables 1 to 4, suggest that the phasestructure described above is required for the characteristics describedabove.

The average grain sizes (μm) of the wires B and D aftermelt-solidification were measured. Specifically, the cut surface of thecasting wire B-1 was etched with nitric acid, and the average grain sizeof the macroscopic structure appearing at the etched surface wasmeasured at a magnification of 7.5 times. This measurement was performedin accordance with the comparison method for estimating average grainsize of copper elongation products specified in JIS H0501. Morespecifically, for the crystal grains of about 0.5 mm or more indiameter, the cut surface was etched with nitric acid and observed at amagnification of 7.5 times; for the crystal grains of about less than0.1 mm in diameter, the cut surface was etched with a mixed solution ofhydrogen peroxide solution and ammonia water and observed at amagnification of 75 time with an optical microscope. The results areshown in Tables 7, 8, and 10.

As shown in Tables 6 to 10, it has been shown that the first to eighthcopper alloy materials, namely, wires A and B, have superior corrosionresistance and seawater resistance to the comparative example wires Cand D, and besides, have superior mechanical properties, such as tensilestrength, and durability to repetitive deformation. In the fifth toeighth copper alloy materials, the crystal grains are notably refined byadding Zr and P in combination. Consequently, the above characteristicswere extremely increased. In particular, the effect of combined use ofZr and P in refining the crystal grains is clearly shown by comparingthe average grain sizes of the combination-processed wires Nos. 501 to505 with those of the second comparative example wires Nos. 2501 to 2505containing the same constituent elements except Zr or P.

The wire drawability of wires A, B, D, and C was evaluated according tothe following criteria. For wires A and C, when the primary processedwire A-3 (diameter: 9 mm) having no crack was obtained from the roundbar A-2 (diameter: 12 mm) by a single wiredrawing operation (processingrate: about 44%), the wire drawability was determined to be good; whenthe primary processed wire A-3 having no crack could not be obtained bythe single wiredrawing operation, but it was obtained by the wiredrawing(two operations) of Example 1 or Comparative Example 1, the wiredrawability was determined to be ordinary; when the primary processedwire A-3 having no crack could not be obtained by the wiredrawing (twooperations) of Example 1 or Comparative Example 1, the wire drawabilitywas determined to be poor. For wires B and D, when the primary processedwire B-2 (diameter: 4.3 mm) having no crack was obtained from thecasting wire B-1 (diameter: 6 mm) by a single wiredrawing operation(processing rate: about 49%), the wire drawability was determined to begood; when the primary processed wire B-2 having no crack could not beobtained by the single wiredrawing operation, but it was obtained by thewiredrawing (two operations) of Example 2 or Comparative Example 2, thewire drawability was determined to be ordinary; when the primaryprocessed wire B-2 having no crack could not be obtained by thewiredrawing (two operations) of Example 2 or Comparative Example 2, thewire drawability was determined to be poor. The results are shown inTables 6 to 10. In these tables, the wires having good drawability areshown as “Good”; the wires having ordinary wire drawability are shown as“fair”; the wire having poor wire drawability are shown as “Poor”.

The castability of wires B and D was evaluated by a castability test. Inthe castability test, the casting wire B-1 was subjected to continuouscasting under the same conditions as in Example 2 or Comparative Example2 in three stages at cast speeds of 3 m/minute, 1.8 m/minute, and 1m/minute. Whether the castability is good or not was determineddepending on the casting speed at which the casting wire B-1 having nodefect was obtained. The results are shown in Tables 7, 8, and 10. Inthe tables, when the casting wire B-1 having no defect was obtained byhigh-speed casting at 3 m/minute, the castability was determined to beexcellent and is shown as “Excellent”; when the casting wire B-1 havingno defect could not be obtained by high-speed casting, but it wasobtained by middle-speed casting at 1.8 m/minute, the castability wasdetermined to be good and is shown as “Good”; when the casting wire B-1having no defect could not be obtained by high-speed casting or middlespeed casting, but it was able to be obtained by low-speed casting at 1m/minute, the castability was determined to be ordinary and is shown as“Fair”; when the casting wire B-1 having no defect could not be obtainedeven by low-speed casting (1 m/minute), the castability was determinedto be poor and is shown as “Poor”. The wired whose castability wasdetermined to be poor (shown as “Poor”) were not subjected to thecastability test, but the castability was evaluated depending on thecasting states in the process for making wires B and D in Example 2 orComparative Example 2. Specifically, when the casting wire B-1 having nodefect could not be obtained in the casting step (low-speed casting at 1m/minute) of the process, the castability was determined to be poorwithout conducting the evaluation test.

As shown in Tables 6 to 10, it has been shown that the first to eighthcopper alloy materials, namely, wires A and B, have superior wiredrawability to the comparative example wires C and D. It has also beenshown that the fifth to eighth copper alloy materials or wires A havenot only superior wire drawability but also superior castability due torefined crystal grains.

Example 3 prepared a square tube-like cultivation net 3 (see FIGS. 1 to3) with a side of 9 m and a depth (length in the vertical direction) of5 m by netting the plastic-processed wire A obtained in Example 1 or thecombination-processed wire B obtained in Example 2 into a rhombicallynetted structure (mesh S: 40 mm). Specifically, plastic-processed wireNo. 405 was netted into cultivation net No. 1, and combination-processedwires Nos. 520, 525, and No. 704 were netted into cultivation nets Nos.2, 3, and 4, respectively, as shown in Table 11.

Comparative Example 3 prepared cultivation nets Nos. 5 and No. 6 havingthe same shape as in Example 3 by respectively netting the firstcomparative example wires Nos. 1004 and 1005, as shown in Table 11.

Fish preserves as shown in FIG. 1 were constructed using cultivationnets Nos. 1 to 6. For each sample number of cultivation nets, two fishpreserves (cultivation nets) were each prepared for culturing yellowtailor salmon. The reinforcing frame 4 (see FIGS. 1 and 4) of about 2000 kgwas attached to each of cultivation nets Nos. 1 to 6 in such a mannerthat the clearance L at the entwined portions 6 a was about 2 mm onaverage.

Then, migratory fish (yellowtail and salmon) were cultured using eachfish preserve in a practical fish farm. When a year had elapsed afterthe start of the cultivation, the maximum wire thickness loss (mm) ofcultivation nets Nos. 1 to 6 was determined. The wire thickness loss wasmeasured at arbitrarily selected 10 points (measurement points) in eachsection of the corner (corner in draft region) of the periphery 3 a inthe draft region (region from 10 cm to 30 cm under the surface of thesea), the region other than the corner of the periphery 3 a in the draftregion (periphery in draft region), the periphery 3 a (region of theperiphery lower than the draft region), and the bottom 3 b. The maximumin the obtained values was defined as the maximum wire thickness loss.The results are shown in Table 11. The wire thickness loss wascalculated by subtracting the thickness of each measurement point aftera year from the initial thickness (4 mm) of the measurement point.

As clearly shown in Table 11, cultivation nets Nos. 1 to 4 of Example 3exhibited a much lower wire thickness loss at each measurement pointthan cultivation nets Nos. 5 and 6 of Comparative Example 3, in spite ofa short period of testing time (one year). Thus, it has been shown thatcultivation nets of Example 3 have superior durability. In addition, theadhesion of marine organisms, such as (“acorn shells”), to cultivationnets Nos. 1 to 6 was hardly found even after a year had elapsed.

TABLE 1 Alloy composition Compositional Phase structure Wire Constituentelement (mass %) value Area ratio (%) No. Cu Zn P Sn Al As Sb Mn Si NiMg Y1 to Y8 Y9 α + γ + δ γ + δ Example 1 101 81.5 17.7 0.8 81.1 4.1 1000 102 90.1 8.5 1.4 89.4 4.0 100 0 103 66.2 32.5 1.3 65.6 2.7 100 2.0 10465.3 33.6 1.1 64.8 2.8 99.0 1.0 105 66.4 32.6 0.05 1.0 65.8 3.0 100 0.1106 64.9 34.1 0.10 0.9 64.2 3.0 100 0.5 107 65.0 33.1 0.10 1.8 63.8 2.1100 7.0 108 65.0 33.4 0.06 1.5 64.1 2.4 100 4.5 201 62.6 36.5 0.8 0.0862.2 3.0 98.0 0.5 202 63.4 36.0 0.5 0.07 63.1 3.3 99.5 0 203 64.3 34.41.2 0.08 63.7 2.7 100 3.5 204 65.5 33.7 0.8 0.04 65.1 3.1 100 0 205 65.533.7 0.8 0.02 65.1 3.1 100 0 206 65.3 33.6 1.0 0.10 0.03 64.7 2.9 1000.5 301 66.0 31.9 1.1 0.7 0.3 65.8 2.9 100 2.0 302 66.5 32.2 1.1 0.265.3 2.9 100 1.5 303 65.5 33.4 1.0 0.2 64.7 2.9 100 1.0 304 64.2 33.50.9 1.1 0.3 64.9 3.0 100 0 305 67.4 30.7 0.05 1.2 0.7 65.4 2.8 100 1.0401 66.8 31.7 1.0 0.4 0.07 65.5 3.0 100 0 402 69.1 28.4 0.04 1.0 1.40.05 66.0 3.1 100 0 403 70.5 26.9 1.3 0.08 0.03 1.2 65.6 2.9 100 4.0 40466.8 31.7 1.0 0.06 0.4 64.9 3.0 100 0.5 405 65.8 33.0 1.1 0.06 0.03 65.32.8 100 0.3

TABLE 2 Alloy composition Compositional Phase structure Wire Constituentelement (mass %) value content ratio Area ratio (%) No. Cu Zn Zr P Snimpurity Y1 to Y8 Y9 Z1 Z2 Z3 α + γ + δ γ + δ Example 2 501 68.8 29.90.0080 0.060 1.20 68.0 2.9 7.5 150.0 20.0 100 0.5 502 72.6 25.9 0.00900.070 1.40 71.7 3.0 7.8 155.6 20.0 100 0 503 75.8 22.1 0.0090 0.050 2.0074.7 2.5 5.6 222.2 40.0 100 0.3 504 80.5 17.0 0.0150 0.080 2.40 79.1 2.45.3 160.0 30.0 100 0 505 90.2 6.2 0.0230 0.090 3.50 88.2 1.9 3.9 152.238.9 100 0 506 66.2 32.7 0.0053 0.060 1.00 65.5 3.0 11.3 188.7 16.7 1000 507 66.0 32.9 0.0015 0.060 1.00 65.3 3.0 40.0 666.7 16.7 100 0.3 50866.5 32.3 0.0090 0.045 1.10 65.8 2.9 5.0 122.2 24.4 100 0 509 66.8 32.00.0120 0.070 1.10 66.0 2.9 5.8 91.7 15.7 100 0 510 66.3 32.6 0.02700.060 1.00 65.6 3.0 2.2 37.0 16.7 100 0 511 66.3 32.6 0.0380 0.080 1.0065.6 3.0 2.1 26.3 12.5 100 0 512 74.1 24.6 0.0180 0.070 1.20 73.3 3.23.9 66.7 17.1 100 0 513 63.2 36.0 0.0150 0.060 0.70 62.7 3.1 4.0 46.711.7 99.0 0.5 514 62.7 36.6 0.0160 0.060 0.60 62.2 3.2 3.8 37.5 10.097.5 1.0 515 66.0 33.9 0.0120 0.050 0.07 65.8 3.9 4.2 5.8 1.4 100 0 51666.5 33.0 0.0090 0.060 0.45 66.1 3.5 6.7 50.0 7.5 100 0 517 66.0 33.20.0140 0.050 0.70 65.5 3.3 3.6 50.0 14.0 100 0 518 76.0 20.5 0.00900.050 3.40 74.2 1.2 5.6 377.8 68.0 100 4.5 519 68.8 29.8 0.0180 0.1801.20 67.7 2.9 10.0 66.7 6.7 100 0.5 520 73.0 25.6 0.0090 0.045 1.30 72.23.1 5.0 144.4 28.9 100 0 521 73.5 24.9 0.0130 0.060 1.50 72.6 2.9 4.6115.4 25.0 100 0.5 522 67.5 30.4 0.0090 0.070 2.00 66.3 2.1 7.8 222.228.6 100 8.0 523 66.5 32.0 0.0080 0.080 1.40 65.6 2.6 10.0 175.0 17.5100 4.5 524 72.2 26.4 0.0150 0.070 1.20 Fe: 0.07 71.5 3.1 4.7 80.0 17.1100 0

TABLE 3 Alloy composition Wire Constituent element (mass %) No. Cu Zn ZrP Sn Al As Sb Mn Si Ni Example 2 525 72.0 26.7 0.015 0.070 1.2 526 71.027.8 0.015 0.070 1.1 527 66.0 32.9 0.035 0.022 1.0 528 66.0 32.8 0.0040.170 1.0 601 66.0 32.9 0.016 0.015 1.0 0.02 602 65.8 33.1 0.009 0.0600.9 0.10 603 66.5 32.3 0.013 0.028 1.1 0.02 604 66.0 32.8 0.009 0.0701.1 0.06 605 66.2 32.8 0.009 0.120 0.8 606 72.8 25.7 0.013 0.090 1.40.04 607 74.2 24.5 0.019 0.060 1.2 701 80.3 17.1 0.016 0.070 2.4 0.14702 68.0 30.7 0.009 0.080 1.1 0.15 703 67.2 30.7 0.015 0.050 1.0 0.700.35 704 72.5 25.8 0.009 0.060 1.3 0.31 705 68.4 29.8 0.012 0.070 1.20.52 706 65.5 31.9 0.010 0.050 0.9 1.20 0.40 707 74.0 24.5 0.015 0.0801.2 0.18 0.07 708 71.5 27.0 0.015 0.080 1.2 0.17 801 67.3 31.3 0.0090.060 1.2 0.08 0.03 802 67.4 31.3 0.012 0.070 1.0 0.20 0.06 803 69.528.2 0.009 0.050 1.0 1.20 804 72.0 25.6 0.011 0.080 1.1 0.05 0.03 1.10805 67.0 31.7 0.012 0.060 1.0 0.06 0.20 Alloy composition Constituentelement Compositional content Phase structure (mass %) value ratio Arearatio (%) Mg impurity Y1 to Y8 Y9 Z1 Z2 Z3 α + γ + δ γ + δ Example 2 Fe:0.03 71.2 3.1 4.7 80.0 17.1 100 0 Ni: 0.03 70.3 3.2 4.7 73.3 15.7 100 065.4 3.0 0.6 28.6 45.5 100 0 65.0 3.0 42.5 250.0 5.9 100 0 65.4 3.0 0.962.5 66.7 100 0.3 65.1 3.0 6.7 100.0 15.0 100 0 65.9 2.9 2.2 84.6 39.3100 0 65.2 2.9 7.8 122.2 15.7 100 1.0 0.110 65.4 3.2 13.3 88.9 6.7 100 071.8 3.0 6.9 107.7 15.6 100 0 0.008 73.4 3.3 3.2 63.2 20.0 100 0 78.62.4 4.4 150.0 34.3 100 0.5 66.7 3.0 8.9 122.2 13.8 100 0 66.7 3.0 3.366.7 20.0 100 0 71.1 3.1 6.7 144.4 21.7 100 0 66.7 2.9 5.8 100.0 17.1100 0 65.9 3.0 5.0 90.0 18.0 100 0.3 73.3 3.2 5.3 80.0 15.0 100 0 70.93.1 5.3 80.0 15.0 100 0 66.4 2.8 6.7 133.3 20.0 100 1.5 66.3 3.0 5.883.3 14.3 100 0 0.050 66.7 3.2 5.6 111.1 20.0 100 0 67.3 3.2 7.3 100.013.8 100 0 65.6 3.0 5.0 83.3 16.7 100 0

TABLE 4 Alloy composition Compositional Phase structure Wire Constituentelement (mass %) value Area ratio (%) No. Cu Zn P Sn Sb Y1 to Y8 Y9 α +γ + δ γ + δ Comparative 1001 61.4 37.6 0.900 0.06 60.9 2.8 94.0 1.0example 1 1002 91.8 7.2 0.900 0.08 91.3 4.6 100 0 1003 65.5 32.0 0.052.500 64.1 1.4 100 12.0 1004 79.8 20.2 0.005 79.8 4.8 100 0 1005 65.134.9 0.007 65.1 3.9 100 0 1006 65.2 34.8 0.005 0.01 65.2 3.9 100 0

TABLE 5 Alloy composition Compositional content Phase structureConstituent element (mass %) value ratio Area ratio (%) Wire No. Cu ZnZr P Sn Sb Ni impurity Y1 to Y8 Y9 Z1 Z2 Z3 α + γ + δ γ + δ Comparative2001 65.5 33.4 0.0004 0.060 1.000 64.8 2.9 150.0 2500.0 16.7 99.7 1.0example 2 2002 66.0 33.0 0.0180 0.008 1.000 0.02 65.5 3.0 0.4 55.6 125.099.8 0 2003 65.7 33.1 0.0750 0.120 1.000 64.8 2.9 1.6 13.3 8.3 100 1.02004 62.0 37.2 0.0160 0.060 0.700 61.5 3.0 3.8 43.8 11.7 96.0 1.0 200561.2 38.0 0.0150 0.070 0.700 60.6 3.0 4.7 46.7 10.0 92.0 2.0 2006 64.835.1 0.0150 0.060 0.005 64.6 3.9 4.0 0.3 0.1 100 0 2007 91.5 5.6 0.01800.100 2.800 89.8 2.7 5.6 155.6 28.0 100 0 2008 90.6 8.8 0.0150 0.0600.500 90.2 4.9 4.0 33.3 8.3 100 0 2009 75.8 19.8 0.0090 0.050 4.300 73.50.2 5.6 477.8 86.0 100 9.0 2010 68.8 29.7 0.0180 0.280 1.200 67.4 2.915.6 66.7 4.3 100 1.0 2011 68.0 29.3 0.0090 0.050 2.600 66.6 1.5 5.6288.9 52.0 100 13.0 2012 73.6 24.5 0.0150 0.070 1.200 0.6 73.7 3.2 4.780.0 17.1 100 0 2013 70.8 27.4 0.0150 0.080 1.200 Fe: 0.55 70.8 3.0 5.380.0 15.0 100 0 2501 68.8 29.9 0.060 1.200 68.0 2.9 100 0.5 2502 72.625.9 0.070 1.400 71.7 3.0 100 0 2503 75.8 22.2 2.000 74.8 2.5 100 0.12504 80.5 17.0 0.080 2.400 79.1 2.4 100 0 2505 90.2 6.2 0.090 3.500 88.21.9 100 0

TABLE 6 maximum corrosion weight depth of loss (mg/cm²) tensile numberof corrosion erosion-corrosion test wire strength elongation fatiguestrength bending wire No. (μm) I II III IV drawability (N/mm²) (%)(N/mm²) sequences Example 1 101 20 25 140 65 310 372 17 152 >5 102 ≦1022 114 68 350 355 14 148 >5 103 90 27 153 85 275 457 18 168 >5 104 13029 180 92 335 445 20 174 >5 105 ≦10 23 108 60 246 Good 436 22 170 >5 10620 26 110 68 273 440 22 168 >5 107 150 34 189 105 335 Fair 479 12 2 10840 26 118 65 256 Fair 468 14 3 201 170 35 202 113 348 450 15 3 202 90 28145 79 313 437 21 5 203 40 25 118 65 275 Good 456 17 4 204 ≦10 22 95 60230 Good 431 23 174 >5 205 70 32 145 90 325 425 24 165 >5 206 ≦10 23 10365 220 Good 439 22 165 >5 301 20 27 112 65 195 483 14 3 302 ≦10 24 11063 220 440 19 5 303 ≦10 26 112 66 245 437 21 168 >5 304 30 27 128 69 160525 14 188 3 305 ≦10 24 102 60 210 475 19 180 >5 401 ≦10 23 108 60 213446 22 174 >5 402 ≦10 23 103 62 188 505 17 185 4 403 35 26 120 70 190508 16 185 3 404 ≦10 27 112 68 210 453 21 165 >5 405 ≦10 24 104 63 218435 22 172 >5

TABLE 7 Corrosion weight loss Average Maximum (mg/cm²) Tensile FatigueNumber of Wire grain size depth of Erosion-corrosion test Wire strengthElongation strength bending No. (μm) corrosion (μm) I II III IVCastability drawability (N/mm²) (%) (N/mm²) sequences Example 2 501 30≦10 21 98 58 205 Excellent Good 445 21 177 >5 502 25 ≦10 19 93 55 192Excellent Good 438 22 174 >5 503 35 ≦10 20 95 54 194 Excellent Good 43122 170 >5 504 65 ≦10 20 94 58 228 Good Good 430 20 166 >5 505 95 ≦10 2189 56 277 Good Good 418 19 155 >5 506 50 ≦10 24 116 66 245 ExcellentGood 436 23 168 >5 507 120 ≦10 25 123 72 266 Good Good 418 20 153 >5 50830 ≦10 24 105 61 228 Excellent Good 446 23 180 >5 509 25 ≦10 23 101 60215 Excellent Good 438 23 178 >5 510 50 ≦10 24 107 62 235 Excellent Good438 22 172 >5 511 90 ≦10 23 108 65 233 Excellent Good 435 21 170 >5 51230 ≦10 23 102 62 226 Excellent Good 420 24 175 >5 513 40 120 29 161 89328 437 22 155 5 514 55 190 34 211 115 372 440 19 153 4 515 40 ≦10 28169 81 392 413 25 151 >5 516 35 ≦10 27 139 70 301 420 25 160 >5 517 30≦10 26 115 72 278 425 23 165 >5 518 35 30 22 99 58 183 Fair 448 12 167 3519 90 ≦10 21 98 59 196 Fair 435 17 4 520 35 ≦10 19 93 55 192 ExcellentGood 438 22 174 >5 521 25 ≦10 19 89 53 182 Excellent Good 428 20 180 >5522 30 100 29 132 81 280 Fair 451 11 3 523 25 40 25 111 65 213 Fair 46214 3 524 120 ≦10 22 103 65 218 Excellent 435 19 165 >5

TABLE 8 Corrosion weight loss Average Maximum (mg/cm²) Tensile FatigueNumber of grain size depth of Erosion-corrosion test Wire strengthElongation strength bending Wire No. (μm) corrosion (μm) I II III IVCastability drawability (N/mm²) (%) (N/mm²) sequences Example 2 525 40≦10 22 102 61 215 Excellent 442 21 170 >5 526 35 ≦10 21 100 59 205Excellent Good 438 22 168 >5 527 180 40 26 128 74 285 422 21 150 >5 528200 20 23 110 67 235 430 17 160 4 601 120 40 26 135 74 285 Good Fair 42218 150 4 602 25 ≦10 23 107 66 243 435 25 173 >5 603 70 20 23 110 67 235Excellent Good 443 21 163 >5 604 30 ≦10 24 108 62 222 442 23 175 >5 60525 ≦10 24 107 69 228 Excellent Good 430 24 168 >5 606 30 ≦10 18 88 54190 442 23 >5 607 40 ≦10 20 90 55 194 428 22 >5 701 70 ≦10 19 90 57 208Excellent Good 433 21 160 >5 702 30 ≦10 23 102 62 200 446 22 >5 703 35≦10 24 108 66 172 485 18 185 4 704 25 ≦10 19 88 51 172 Excellent Good446 23 175 >5 705 25 ≦10 21 94 55 180 Excellent Good 455 23 185 >5 70640 ≦10 24 110 67 145 478 18 190 4 707 35 ≦10 19 104 59 198 452 20 180 >5708 180 ≦10 23 108 67 230 Good Fair 438 18 5 801 30 ≦10 23 101 58 185Excellent Good 445 20 174 >5 802 25 ≦10 23 98 60 184 440 23 >5 803 25≦10 21 99 55 152 465 20 >5 804 35 ≦10 23 100 59 165 471 20 >5 805 35 ≦1022 105 60 198 450 22 >5

TABLE 9 Corrosion weight loss Maximum (mg/cm²) Tensile Fatigue Number ofWire depth of Erosion-corrosion test Wire strength Elongation strengthbending No. corrosion (μm) I II III IV drawability (N/mm²) (%) (N/mm²)sequences Comparative 1001 400 51 330 164 535 Fair 488 11 2 example 11002 ≦10 29 205 72 445 340 16 >5 1003 Poor 1004 140 34 235 95 495 335 20130 >5 1005 250 39 258 112 500 398 22 142 >5 1006 240 38 260 113 493 39722 143 >5

TABLE 10 Maximum Corrosion weight loss Average depth of (mg/cm²) TensileFatigue Number of Wire grain size corrosion Erosion-corrosion test Wirestrength Elongation strength bending No. (μm) (μm) I II III IVCastability drawability (N/mm²) (%) (N/mm²) sequences Comparative 2001800 90 28 145 90 345 Fair Poor 399 15 135 3 example 2 2002 700 90 27 15380 320 Fair Poor 405 16 138 3 2003 200 ≦10 24 110 64 240 Good Fair 42520 162 5 2004 180 380 47 325 170 498 456 16 150 3 2005 350 480 55 350203 566 Poor 478 11 148 2 2006 40 20 33 216 94 495 410 25 150 >5 2007250 ≦10 25 126 68 402 375 17 140 5 2008 350 ≦10 26 168 75 456 335 15 1334 2009 40 Poor 2010 150 Poor 2011 25 Poor 2012 400 Poor 2013 300 30 27113 82 215 Fair Poor 470 14 160 3 2501 1000 40 24 118 92 345 Fair Fair405 12 135 3 2502 1200 Poor 2503 1300 Poor 2504 1500 Poor 2505 1500 Poor

TABLE 11 Wire thickness loss (mm) Cultivation Wire Corner in Peripheryin net No. No. Cultured fish draft region draft region Periphery BottomExample 3 1 405 Yellowtail 0.44 0.36 0.09 0.57 Salmon 0.42 0.35 0.030.05 2 509 Yellowtail 0.39 0.34 0.08 0.53 Salmon 0.38 0.33 0.03 0.05 3521 Yellowtail 0.36 0.3 0.06 0.49 Salmon 0.34 0.29 0.02 0.04 4 704Yellowtail 0.37 0.32 0.07 0.45 Salmon 0.36 0.32 0.03 0.05 Comparative 51004 Yellowtail 0.8 0.62 0.25 1.35 example 3 Salmon 0.85 0.64 0.08 0.1 61005 Yellowtail 1.05 0.75 0.28 2.0 Salmon 0.99 0.77 0.12 0.15

1. A copper alloy material in wire or bar form for forming a nettedstructure used in seawater under harsh conditions, wherein the nettedstructure is exposed to water or waves running at high speed andrubbing, and wherein the copper alloy material comprises a compositionincluding: (a) 62 to 91 mass % of Cu; (b) 0.6 to 3 mass % of Sn; (c) oneor more elements selected from the group consisting of 0.02 to 1.5 mass% of Al, and 0.02 to 1.9 mass % of Si; and (d) the balance being Zn,wherein the composition satisfies the relationship derived from the Cucontent [Cu], and the Sn content [Sn], in terms of mass %,62≦[Cu]−0.5[Sn]≦90, wherein the copper alloy material has a phasestructure including an α phase, a γ phase, and a δ phase, and the totalarea ratio of the α, γ, and δ phases is 95 to 100%, and the copper alloymaterial forms an Al—Sn coating or a Si—Sn coating when in seawater. 2.The copper alloy material according to claim 1, wherein the compositionfurther contains one or more elements X1 selected from the groupconsisting of 0.02 to 0.25 mass % of As, 0.02 to 0.25 mass % of Sb,0.001 to 0.2 mass % of Mg, and 0.01 to 0.25 mass % of P, and thecomposition satisfies the relationship derived from the Cu content [Cu],the Sn content [Sn], the Al content [Al], the Si content [Si], the Pcontent [P], and the X1 total content [X1] except content [P] in termsof mass %,62≦[Cu]−0.5[Sn]−3[P]−0.5[X1]−3.5[Si]−1.8[Al]≦90.
 3. The copper alloymaterial according to claim 1, wherein the composition further containsone or more elements selected from the group consisting of 0.05 to 1.5mass % of Mn, and 0.005 to 0.5 mass % of Ni, and the compositionsatisfies the relationship derived from the Cu content [Cu], the Sncontent [Sn], the Al content [Al], the Mn content [Mn], the Si content[Si], and the Ni content [Ni] in terms of mass %,62≦[Cu]−0.5[Sn]−3.5[Si]−1.8[Al]+[Mn]+[Ni]≦90.
 4. The copper alloymaterial according to claim 2, wherein the composition further containsone or more elements selected from the group consisting of 0.05 to 1.5mass % of Mn, and 0.005 to 0.5 mass % of Ni, and the compositionsatisfies the relationship derived from the Cu content [Cu], the Sncontent [Sn], the P content [P], the X1 total content [X1] exceptcontent [P], the Al content [Al], the Mn content [Mn], the Si content[Si], and the Ni content [Ni] in terms of mass %,62≦[Cu]−0.5[Sn]−3[P]−0.5[X1]−3.5[Si]−1.8[Al]+[Mn]+[Ni]≦90.
 5. The copperalloy material according to claim 1, wherein the phase structure has atotal area ratio of the γ and δ phases of 10% or less.
 6. The copperalloy material according to claim 5, wherein the Cu content [Cu] and theSn content [Sn] satisfy the relationship 1≦0.06[Cu]−[Sn]≦4.5 in terms ofmass %.
 7. A copper alloy material in wire or bar form for forming anetted structure used in seawater, the copper alloy material comprisinga composition containing: (a) 62 to 91 mass % of Cu; (b) 0.6 to 3 mass %of Sn; (c) 0.0008 to 0.045 mass % of Zr; (d) 0.01 to 0.25 mass % of P;and (e) the balance being Zn, wherein the composition satisfies therelationship derived from the Cu content [Cu], Sn content [Sn], and Pcontent [P] in terms of mass %, 62≦[Cu]−0.5[Sn]−3[P]≦90, wherein thecopper alloy material has a phase structure including an α phase, a γphase, and a δ phase, wherein the total area ratio of the α, γ, and δphases is 95 to 100%, and the average grain size is 0.2 mm or less aftermelt-solidification.
 8. The copper alloy material according to claim 7,wherein the composition further contains at least one element X3selected from the group consisting of 0.02 to 0.25 mass % of As, 0.02 to0.25 mass % of Sb, and 0.001 to 0.2 mass % of Mg, and the compositionsatisfies the relationship derived from the Cu content [Cu], Sn content[Sn], P content [P], and X3 total content [X3] in terms of mass %:62≦[Cu]−0.5[Sn]−3[P]−0.5[X3]≦90, and wherein the total area ratio of theα, γ, δ phases is 95 to 100% and the average grain size is 0.2 mm orless after melt-solidification.
 9. The copper alloy material accordingto claim 7, wherein the composition further contains at least oneelement X4 selected from the group consisting of 0.02 to 1.5 mass % ofAl, 0.05 to 1.5 mass % of Mn, 0.02 to 1.9 mass % of Si, and 0.005 to 0.5mass % of Ni, and the composition satisfies the relationship derivedfrom the Cu content [Cu], Sn content [Sn], P content [P], Al content[Al], Mn content [Mn], Si content [Si], and Ni content [Ni] in terms ofmass %: 62≦[Cu]−0.5[Sn]−3[P]−3.5[Si]−1.8[Al]+[Mn]+[Ni]≦90, and whereinthe total area ratio of the α, γ, δ phases is 95 to 100% and the averagegrain size is 0.2 mm or less after melt-solidification.
 10. The copperalloy material according to claim 8, wherein the composition furthercontains at least one element X4 selected from the group consisting of0.02 to 1.5 mass % of Al, 0.05 to 1.5 mass % of Mn, 0.02 to 1.9 mass %of Si, and 0.005 to 0.5 mass % of Ni, and the composition satisfies therelationship derived from the Cu content [Cu], Sn content [Sn], Pcontent [P], X3 total content [X3], Al content [Al], Mn content [Mn], Sicontent [Si], and Ni content [Ni] in terms of mass %:62≦[Cu]−0.5[Sn]−3[P]−0.5[X3]−3.5[Si]−1.8[Al]+[Mn]+[Ni]≦90, and whereinthe total area ratio of the α, γ, δ phases is 95 to 100% and the averagegrain size is 0.2 mm or less after melt-solidification.
 11. The copperalloy material according to claim 7, wherein the Sn content [Sn], Zrcontent [Zr], and P content [P] of the composition satisfy therelationships 0.5≦[P]/[Zr]≦150, 1≦[Sn]/[Zr]≦3000, and 0.2≦[Sn]/[P]≦250in terms of mass %.
 12. The copper alloy material according to claim 7,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 13. The copper alloy material according to claim 12, theCu content [Cu] and Sn content [Sn] of the composition satisfy therelationship 1≦0.06[Cu]−[Sn]≦4.5 in terms of mass %.
 14. The copperalloy material according to claim 11, wherein the primary crystal inmelt-solidification is in the α phase.
 15. The copper alloy materialaccording to claim 7, wherein the composition contains an inevitableimpurity being Fe, or Ni, or Fe and Ni, and the contents of inevitableimpurities Fe and Ni are each 0.5 mass % or less.
 16. The copper alloymaterial according to claim 11, wherein the copper alloy material is acast-processed wire or bar, or a combination-processed wire or barproduced by subjecting the cast-processed wire or bar to plasticprocessing.
 17. A method for manufacturing the copper alloy material inwire or bar form set forth in claim 7, the method comprising a castingstep in which Zr is added in a form of a copper alloy containing Zrimmediately before pouring, thus preventing the addition of an oxide, ora sulfide of Zr, or an oxide and a sulfide of Zr.
 18. The method formanufacturing the copper alloy material according to claim 17, whereinthe copper alloy containing Zr is a Cu—Zr alloy, a Cu—Zn—Zr alloy, or aCu—Zr- or Cu—Zn—Zr-based alloy further containing at least one elementselected from the group consisting of P, Mg, Al, Sn, Mn, and B.
 19. Anetted structure used in seawater, comprising the copper alloy materialin wire or bar form as set forth in claim 2, wherein the copper alloymaterial is formed into a net or a grid.
 20. The netted structure usedin seawater according to claim 19, wherein the copper alloy material isa waved wire having curved portions, and the netted structure has arhombically netted form made by arranging a large number of the wavedwires in parallel such that the adjacent waved wires are entwined witheach other at the curved portions.
 21. The netted structure used inseawater according to claim 20, wherein the netted structure isconfigured as a fish cultivation net.
 22. The netted structure used inseawater according to claim 21, wherein the fish cultivation netincludes a reinforcing frame attached along the lower edge of the net ina ring-shaped manner, and the reinforcing frame maintains the shape ofthe lower edge of the net and applies a downward tension to the net. 23.The netted structure used in seawater according to claim 22, wherein thereinforcing frame is formed of a pipe made of the same copper alloy asthe material forming the net.
 24. The copper alloy material according toclaim 2, wherein the phase structure has a total area ratio of the γ andδ phases of 10% or less.
 25. The copper alloy material according toclaim 24, wherein the Cu content [Cu] and the Sn content [Sn] satisfythe relationship 1≦0.06[Cu]−[Sn]≦4.5 in terms of mass %.
 26. The copperalloy material according to claim 3, wherein the phase structure has atotal area ratio of the γ and δ phases of 10% or less.
 27. The copperalloy material according to claim 26, wherein the Cu content [Cu] andthe Sn content [Sn] satisfy the relationship 1≦0.06[Cu]−[Sn]≦4.5 interms of mass %.
 28. The copper alloy material according to claim 4,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 29. The copper alloy material according to claim 28,wherein the Cu content [Cu] and the Sn content [Sn] satisfy therelationship 1≦0.06[Cu]−[Sn]≦4.5 in terms of mass %.
 30. The copperalloy material according to claim 8, wherein the Sn content [Sn], Zrcontent [Zr], and P content [P] of the composition satisfy therelationships 0.5≦[P]/[Zr]≦150, 1≦[Sn]/[Zr]≦3000, and 0.2≦[Sn]/[P]≦250in terms of mass %.
 31. The copper alloy material according to claim 30,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 32. The copper alloy material according to claim 9,wherein the Sn content [Sn], Zr content [Zr], and P content [P] of thecomposition satisfy the relationships 0.5≦[P]/[Zr]≦150,1≦[Sn]/[Zr]≦3000, and 0.2≦[Sn]/[P]≦250 in terms of mass %.
 33. Thecopper alloy material according to claim 32, wherein the phase structurehas a total area ratio of the γ and δ phases of 10% or less.
 34. Thecopper alloy material according to claim 10, wherein the Sn content[Sn], Zr content [Zr], and P content [P] of the composition satisfy therelationships 0.5≦[P]/[Zr]≦150, 1≦[Sn]/[Zr]≦3000, and 0.2≦[Sn]/[P]≦250in terms of mass %.
 35. The copper alloy material according to claim 34,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 36. The copper alloy material according to claim 8,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 37. The copper alloy material according to claim 9,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 38. The copper alloy material according to claim 10,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 39. The copper alloy material according to claim 11,wherein the phase structure has a total area ratio of the γ and δ phasesof 10% or less.
 40. The copper alloy material according to claim 36, theCu content [Cu] and Sn content [Sn] of the composition satisfy therelationship 1≦0.06[Cu]−[Sn]≦4.5 in terms of mass %.
 41. The copperalloy material according to claim 37, the Cu content [Cu] and Sn content[Sn] of the composition satisfy the relationship 1≦0.06[Cu]−[Sn]≦4.5 interms of mass %.
 42. The copper alloy material according to claim 38,the Cu content [Cu] and Sn content [Sn] of the composition satisfy therelationship 1≦0.06[Cu]−[Sn]≦4.5 in terms of mass %.
 43. The copperalloy material according to claim 31, the Cu content [Cu] and Sn content[Sn] of the composition satisfy the relationship 1≦0.06[Cu]−[Sn]≦4.5 interms of mass %.
 44. The copper alloy material according to claim 33,the Cu content [Cu] and Sn content [Sn] of the composition satisfy therelationship 1≦0.06[Cu]−[Sn]≦4.5 in terms of mass %.
 45. The copperalloy material according to claim 35, the Cu content [Cu] and Sn content[Sn] of the composition satisfy the relationship 1≦0.06[Cu]−[Sn]≦4.5 interms of mass %.
 46. The copper alloy material according to claim 39,the Cu content [Cu] and Sn content [Sn] of the composition satisfy therelationship 1≦0.06[Cu]−[Sn]≦4.5 in terms of mass %.
 47. The copperalloy material according to claim 32, wherein the primary crystal inmelt-solidification is in the α phase.
 48. The copper alloy materialaccording to claim 34, wherein the primary crystal inmelt-solidification is in the α phase.
 49. The copper alloy materialaccording to claim 44, wherein the copper alloy material has a crystalstructure whose dendrite network is fractured after melt-solidification.50. The copper alloy material according to claim 45, wherein thetwo-dimensional crystal grain structure is in a circular form or a formsimilar to the circular form after melt-solidification.
 51. The copperalloy material according to claim 49, wherein the two-dimensionalcrystal grain structure is in a circular form or a form similar to thecircular form after melt-solidification.
 52. The copper alloy materialaccording to claim 8, wherein the composition contains an inevitableimpurity being Fe, or Ni, or Fe and Ni, and the contents of inevitableimpurities Fe and Ni are each 0.5 mass % or less.
 53. The copper alloymaterial according to claim 9, wherein the composition contains aninevitable impurity being Fe, or Ni, or Fe and Ni, and the contents ofinevitable impurities Fe and Ni are each 0.5 mass % or less.
 54. Thecopper alloy material according to claim 10, wherein the compositioncontains an inevitable impurity being Fe, or Ni, or Fe and Ni, and thecontents of inevitable impurities Fe and Ni are each 0.5 mass % or less.55. The copper alloy material according to claim 11, wherein thecomposition contains an inevitable impurity being Fe, or Ni, or Fe andNi, and the contents of inevitable impurities Fe and Ni are each 0.5mass % or less.
 56. The copper alloy material according to claim 32,wherein the composition contains an inevitable impurity being Fe, or Ni,or Fe and Ni, and the contents of inevitable impurities Fe and Ni areeach 0.5 mass % or less.
 57. The copper alloy material according toclaim 13, wherein the composition contains an inevitable impurity beingFe, or Ni, or Fe and Ni, and the contents of inevitable impurities Feand Ni are each 0.5 mass % or less.
 58. The copper alloy materialaccording to claim 40, wherein the composition contains an inevitableimpurity being Fe, or Ni, or Fe and Ni, and the contents of inevitableimpurities Fe and Ni are each 0.5 mass % or less.
 59. The copper alloymaterial according to claim 41, wherein the composition contains aninevitable impurity being Fe, or Ni, or Fe and Ni, and the contents ofinevitable impurities Fe and Ni are each 0.5 mass % or less.
 60. Thecopper alloy material according to claim 24, wherein the copper alloymaterial is a plastic-processed wire or bar produced by plasticprocessing of a casting material.
 61. The copper alloy materialaccording to claim 28, wherein the copper alloy material is aplastic-processed wire or bar produced by plastic processing of acasting material.
 62. The copper alloy material according to claim 25,wherein the copper alloy material is a plastic-processed wire or barproduced by plastic processing of a casting material.
 63. The copperalloy material according to claim 29, wherein the copper alloy materialis a plastic-processed wire or bar produced by plastic processing of acasting material.
 64. The copper alloy material according to claim 30,wherein the copper alloy material is a cast-processed wire or bar, or acombination-processed wire or bar produced by subjecting thecast-processed wire or bar to plastic processing.
 65. The copper alloymaterial according to claim 32, wherein the copper alloy material is acast-processed wire or bar, or a combination-processed wire or barproduced by subjecting the cast-processed wire or bar to plasticprocessing.
 66. The copper alloy material according to claim 34, whereinthe copper alloy material is a cast-processed wire or bar, or acombination-processed wire or bar produced by subjecting thecast-processed wire or bar to plastic processing.
 67. The copper alloymaterial according to claim 33, wherein the copper alloy material is acast-processed wire or bar, or a combination-processed wire or barproduced by subjecting the cast-processed wire or bar to plasticprocessing.
 68. The copper alloy material according to claim 35, whereinthe copper alloy material is a cast-processed wire or bar, or acombination-processed wire or bar produced by subjecting thecast-processed wire or bar to plastic processing.
 69. The copper alloymaterial according to claim 39, wherein the copper alloy material is acast-processed wire or bar, or a combination-processed wire or barproduced by subjecting the cast-processed wire or bar to plasticprocessing.
 70. The copper alloy material according to claim 43, whereinthe copper alloy material is a cast-processed wire or bar, or acombination-processed wire or bar produced by subjecting thecast-processed wire or bar to plastic processing.
 71. The copper alloymaterial according to claim 44, wherein the copper alloy material is acast-processed wire or bar, or a combination-processed wire or barproduced by subjecting the cast-processed wire or bar to plasticprocessing.
 72. The copper alloy material according to claim 46, whereinthe copper alloy material is a cast-processed wire or bar, or acombination-processed wire or bar produced by subjecting thecast-processed wire or bar to plastic processing.
 73. A method formanufacturing the copper alloy material in wire or bar form as set forthin claim 8, the method comprising a casting step in which Zr is added ina form of a copper alloy containing Zr immediately before pouring, thuspreventing the addition of an oxide, or a sulfide of Zr, or an oxide anda sulfide of Zr.
 74. The method for manufacturing the copper alloymaterial according to claim 73, wherein the copper alloy containing Zris a Cu—Zr alloy, a Cu—Zn—Zr alloy, or a Cu—Zr- or Cu—Zn—Zr-based alloyfurther containing at least one element selected from the groupconsisting of P, Mg, Al, Sn, Mn, and B.
 75. A method for manufacturingthe copper alloy material in wire or bar form as set forth in claim 9,the method comprising a casting step in which Zr is added in a form of acopper alloy containing Zr immediately before pouring, thus preventingthe addition of an oxide, or a sulfide of Zr, or an oxide and a sulfideof Zr.
 76. The method for manufacturing the copper alloy materialaccording to claim 75, wherein the copper alloy containing Zr is a Cu—Zralloy, a Cu—Zn—Zr alloy, or a Cu—Zr- or Cu—Zn—Zr-based alloy furthercontaining at least one element selected from the group consisting of P,Mg, Al, Sn, Mn, and B.
 77. A method for manufacturing the copper alloymaterial in wire or bar form as set forth in claim 10, the methodcomprising a casting step in which Zr is added in a form of a copperalloy containing Zr immediately before pouring, thus preventing theaddition of an oxide, or a sulfide of Zr, or an oxide and a sulfide ofZr.
 78. A netted structure used in seawater, comprising the copper alloymaterial in wire or bar form as set forth in claim 1, wherein the copperalloy material is formed into a net or a grid.
 79. A netted structureused in seawater, comprising the copper alloy material in wire or barform as set forth in claim 3, wherein the copper alloy material isformed into a net or a grid.
 80. A netted structure used in seawater,comprising the copper alloy material in wire or bar form as set forth inclaim 4, wherein the copper alloy material is formed into a net or agrid.
 81. A netted structure used in seawater, comprising the copperalloy material in wire or bar form as set forth in claim 6, wherein thecopper alloy material is formed into a net or a grid.
 82. A nettedstructure used in seawater, comprising the copper alloy material in wireor bar form as set forth in claim 7, the copper alloy material beingformed into a net or a grid.
 83. A netted structure used in seawater,comprising the copper alloy material in wire or bar form as set forth inclaim 8, the copper alloy material being formed into a net or a grid.84. A netted structure used in seawater, comprising the copper alloymaterial in wire or bar form as set forth in claim 9, the copper alloymaterial being formed into a net or a grid.
 85. A netted structure usedin seawater, comprising the copper alloy material in wire or bar form asset forth in claim 10, the copper alloy material being formed into a netor a grid.
 86. A netted structure used in seawater, comprising thecopper alloy material in wire or bar form as set forth in claim 11, thecopper alloy material being formed into a net or a grid.
 87. A nettedstructure used in seawater, comprising the copper alloy material in wireor bar form as set forth in claim 25, wherein the copper alloy materialis formed into a net or a grid.
 88. A netted structure used in seawater,comprising the copper alloy material in wire or bar form as set forth inclaim 27, wherein the copper alloy material is formed into a net or agrid.
 89. A netted structure used in seawater, comprising the copperalloy material in wire or bar form as set forth in claim 29, wherein thecopper alloy material is formed into a net or a grid.
 90. A nettedstructure used in seawater, comprising the copper alloy material in wireor bar form as set forth in claim 30, the copper alloy material beingformed into a net or a grid.
 91. A netted structure used in seawater,comprising the copper alloy material in wire or bar form as set forth inclaim 32, the copper alloy material being formed into a net or a grid.92. A netted structure used in seawater, comprising the copper alloymaterial in wire or bar form as set forth in claim 34, the copper alloymaterial being formed into a net or a grid.
 93. A netted structure usedin seawater, comprising the copper alloy material in wire or bar form asset forth in claim 15, the copper alloy material being formed into a netor a grid.
 94. A netted structure used in seawater, comprising thecopper alloy material in wire or bar form as set forth in claim 53, thecopper alloy material being formed into a net or a grid.
 95. The nettedstructure used in seawater according to claim 80, wherein the copperalloy material is a waved wire having curved portions, and the nettedstructure has a rhombically netted form made by arranging a large numberof the waved wires in parallel such that the adjacent waved wires areentwined with each other at the curved portions.
 96. The nettedstructure used in seawater according to claim 82, wherein the copperalloy material is a waved wire having curved portions, and the nettedstructure has a rhombically netted form made by arranging a large numberof the waved wires in parallel such that the adjacent waved wires areentwined with each other at the curved portions.
 97. The nettedstructure used in seawater according to claim 83, wherein the copperalloy material is a waved wire having curved portions, and the nettedstructure has a rhombically netted form made by arranging a large numberof the waved wires in parallel such that the adjacent waved wires areentwined with each other at the curved portions.
 98. The nettedstructure used in seawater according to claim 84, wherein the copperalloy material is a waved wire having curved portions, and the nettedstructure has a rhombically netted form made by arranging a large numberof the waved wires in parallel such that the adjacent waved wires areentwined with each other at the curved portions.
 99. The nettedstructure used in seawater according to claim 95, wherein the nettedstructure is configured as a fish cultivation net.
 100. The nettedstructure used in seawater according to claim 96, wherein the nettedstructure is used as a fish cultivation net.
 101. The netted structureused in seawater according to claim 97, wherein the netted structure isused as a fish cultivation net.
 102. The netted structure used inseawater according to claim 98, wherein the netted structure is used asa fish cultivation net.
 103. The netted structure used in seawateraccording to claim 99, wherein the fish cultivation net includes areinforcing frame attached along the lower edge of the net in aring-shaped manner, and the reinforcing frame maintains the shape of thelower edge of the net and applies a downward tension to the net. 104.The netted structure used in seawater according to claim 100, whereinthe fish cultivation net includes a reinforcing frame attached along thelower edge of the net in a ring-shaped manner, and the reinforcing framemaintains the shape of the lower edge of the net and applies a downwardtension to the net.
 105. The netted structure used in seawater accordingto claim 101, wherein the fish cultivation net includes a reinforcingframe attached along the lower edge of the net in a ring-shaped manner,and the reinforcing frame maintains the shape of the lower edge of thenet and applies a downward tension to the net.
 106. The netted structureused in seawater according to claim 102, wherein the fish cultivationnet includes a reinforcing frame attached along the lower edge of thenet in a ring-shaped manner, and the reinforcing frame maintains theshape of the lower edge of the net and applies a downward tension to thenet.
 107. The netted structure used in seawater according to claim 103,wherein the reinforcing frame is formed of a pipe made of the samecopper alloy as the material forming the net.
 108. A copper alloymaterial in wire or bar form for forming a netted structure used inseawater under harsh conditions, wherein the netted structure is exposedto water or waves running at high speed and rubbing, and wherein thecopper alloy material comprises a composition that does not include Mnand that does not include Ni, wherein the composition includes: (a) 62to 91 mass % of Cu; (b) 0.6 to 3 mass % of Sn; (c) one or more elementsselected from the group consisting of 0.02 to 1.5 mass % of Al, and 0.02to 1.9 mass % of Si; and (d) the balance being Zn, wherein thecomposition satisfies the relationship derived from the Cu content [Cu],the Sn content [Sn], the Al content [Al], and the Si content [Si], interms of mass %, 62≦[Cu]−0.5[Sn]−3.5[Si]−1.8[Al]≦90, wherein the copperalloy material has a phase structure including an α phase, a γ phase,and a δ phase, and the total area ratio of the α, γ, and δ phases is 95to 100%, and the copper alloy material forms an Al—Sn coating or a Si—Sncoating when in seawater.
 109. A copper alloy material in wire or barform forming a netted structure used in seawater under harsh conditions,wherein the netted structure is exposed to water or waves running athigh speed and rubbing, and wherein the copper alloy material comprisesa composition including: (a) 62 to 91 mass % of Cu; (b) 0.6 to 3 mass %of Sn; (c) one or more elements selected from the group consisting of0.02 to 1.5 mass % of Al, and 0.02 to 1.9 mass % of Si; and (d) thebalance being Zn, wherein the composition satisfies the relationshipderived from the Cu content [Cu], the Sn content [Sn], the Al content[Al], and the Si content [Si], in terms of mass %, 62≦[Cu]−0.5[Sn]≦90,wherein the copper alloy material has a phase structure including an αphase, a γ phase, and a δ phase, and the total area ratio of the α, γ,and δ phases is 95 to 100%, and the copper alloy material has an Al—Snsurface coating or a Si—Sn surface coating.
 110. The copper alloymaterial according to claim 1, wherein the phase structure does notinclude a β phase, and the γ phase is arranged into fractured sphericalfragments.
 111. The copper alloy material according to claim 1, whereinthe phase structure includes a β phase, and the γ phase and the β phaseare arranged into fractured spherical fragments.
 112. The copper alloymaterial according to claim 43, wherein the copper alloy material has acrystal structure whose dendrite network is fractured aftermelt-solidification.
 113. The copper alloy material according to claim112, wherein the two-dimensional crystal grain structure is in acircular form or a form similar to the circular form aftermelt-solidification.